---
product_id: 40506837
title: "New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years)"
brand: "kstpower"
price: "KSh16933"
currency: KES
in_stock: false
reviews_count: 6
url: https://www.desertcart.co.ke/products/40506837-new-f999b-super-sensitive-listen-thru-wall-contact-probe-microphone
store_origin: KE
region: Kenya
---

# 4 audio channels for crisp clarity 24h continuous battery life Penetrates cement, metal, wood & more New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years)

**Brand:** kstpower
**Price:** KSh16933
**Availability:** ❌ Out of Stock

## Summary

> 🔍 Hear what others can’t—unlock hidden conversations with pro-grade stealth tech!

## Quick Answers

- **What is this?** New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years) by kstpower
- **How much does it cost?** KSh16933 with free shipping
- **Is it available?** Currently out of stock
- **Where can I buy it?** [www.desertcart.co.ke](https://www.desertcart.co.ke/products/40506837-new-f999b-super-sensitive-listen-thru-wall-contact-probe-microphone)

## Best For

- kstpower enthusiasts

## Why This Product

- Trusted kstpower brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Discreet & Private Use:** Private listing ensures your purchase stays off feedback profiles—total confidentiality.
- • **Rugged & Reliable Build:** Durable metal housing with premium quartz crystal piezo microphone for superior detection.
- • **All-Day Surveillance Ready:** Up to 24 hours continuous monitoring on a single lithium battery charge.
- • **Unmatched Wall Penetration:** Hear through cement, metal, wood, brick & glass with supreme sensitivity.
- • **Quad-Channel Audio Precision:** Four frequency channels (1200Hz, 800Hz, 200Hz) for tailored sound clarity.

## Overview

The New F999B Super Sensitive Listen Thru-wall Contact/Probe Microphone Amplifier System is a professional-grade device designed to detect sound through solid surfaces like cement, metal, wood, and brick. Featuring four audio channels, up to 20,000x amplification, and 24-hour battery life, it offers unparalleled sensitivity and continuous monitoring. Its rugged metal housing and premium quartz crystal piezo microphone ensure durability and superior sound detection. Ideal for discreet surveillance, it comes with a private purchase option and a 5-year warranty, making it a top choice for serious professionals.

## Description

The ultimate professional listen through wall system that can hear sound through concrete, metal, wood, brick in fact any solid surface. This serious piece of kit is not for the faint hearted, be warned you can hear through indoor and outdoor walls. Some surfaces work better than others and density / thickness can also restrict its performance. We have received varied results as it depends entirely on the surface you use and many other factors such as distance and volume. Place the Sonde contact microphone to the surface of interest and listen it has variable gain and volume settings. You may need to experiment further with the position for better results and we can not guarantee results first time every time. We guarantee it will hear audible sound through any door or single brick / cavity walls. Anything else is not guaranteed and returns for using this beyond it's means is not accepted. Unless it is faulty not hearing through doors, windows, internal walls etc. Another serious matter is the headphones used, included is good quality earbuds but if you use noise cancelling headphones costing £50-£200 this improves the sound hugely. F-999B professional listen through wall spy ear is a highly sensitive contact and probe microphone amplifier system. Both microphone and amplifier are built into a strong metal housings for durability. Enhanced quality sound and performance capable of listening to conversations in adjoining rooms and houses. High quality earbuds a built in lithium battery and all accessories needed to achieve the job. The highest sensitive contact microphone available with superior detection ability using best quartz crystal piezo. This quality component is more sensitive and clearer than anything else out there and if this does not work then nothing will for less than £100. Package includes: Sonde contact microphone Probe / Needle microphone Microphone / Headphone Amplifier 2.5mm-3.5mm stereo record lead Charger and Metal case

Review: Great Basic Device - Reading others views here, I thought I would add my own opinion. Definitely a Chinese manufacture, and quality is so-so. Packaging and case quality are frankly horrible. That said, I am loving this device. Do not try to hold the probe manually; you cannot keep it still enough for decent signal. Nor can you tape to wall firmly enough. Find or create a flat surface to adjoin the wall - such as a large, flat book. Then find something nonmetallic and HEAVY to press against the fixture to create non-moving firm contact. The sound quality isn't what you would get from a mic inside the target area - but it is VERY close. I use an Olympus LS-P2 recorder that has two 3.5 openings - one for external mic and the other for a standard headphone. I tried buying a cheaper Olympus MP3 recorder for dedicated use with this mic, but it didn't process the incoming signal well; so you really have to get a decent recording unit assuming you do intend to connect the unit to a digital recorder. The unit also has several ports - FM transmitter (which I don't use), DC Charging port, Mic (for wall probe), REC - direct connection to your digital recorder and EAR - for headphones. So you can monitor the recording either through the device or through your recorder. As far as the 'do not overcharge' message - Ok, that's a bit unusual, but I just recharge when I am on hand to monitor it occasionally; it's probably not something you want to run off and leave. When the light turns green, it's done and you can unplug - not a big deal IMO and certainly not a dealbreaker or anything justifying less stars or a neg review. By the way the battery life is great. I had to leave this on for about 8 hours unattended and the unit worked very well. My advice is shop around. As good as this is, it is clearliy 80s/90s tech; it's enough for my use, but there are probably better things out there albeit more expensive. $105 for this kit is completely justifiable.
Review: product critique - satisfied

## Features

- HIGHEST SENSITIVE LISTEN THROUGH WALL / CEILING CONTACT & PROBE MICROPHONE SET
- THIS IS A PRIVATE LISTING DUE TO THE NATURE OF THIS PRODUCT. YOU CAN PURCHASE THIS PRODUCT AND IT WILL NOT SHOW UP ON YOUR FEEDBACK PROFILE.
- Penetrable surfaces: Cement, Metal, Wood, Iron, Glass, Plastic, Brick Working time: Continuos monitoring up to 24 hours Headphone output: 3.5mm stereo @ 250mW Four audio channel: 1200Hz, 800Hz, 200Hz
- Maximum gain amplification: 20000 times Battery type: 3.7v lithium battery Microphone sensitivity: -70db Current consumption: 10mA
- Record line output: 2.5mm stereo Jack socket Battery capacity: 250mA

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B01L9AMY9Y |
| Audio Sensitivity | 70 Decibels |
| Best Sellers Rank | #237,214 in Electronics ( See Top 100 in Electronics ) #1,441 in Audio Component Amplifiers |
| Customer Reviews | 3.5 3.5 out of 5 stars (25) |
| Date First Available | August 30, 2016 |
| EU Spare Part Availability Duration | 5 Years |
| Frequency Response | 20 KHz |
| Impedance | 32 Ohms |
| Is Discontinued By Manufacturer | No |
| Item Weight | 1.49 pounds |
| Item dimensions L x W x H | 9.06 x 7.09 x 2.76 inches |
| Item model number | F999B |
| Manufacturer | Kstpower |
| Material | Wood |
| Microphone Form Factor | Mini |
| Number of Channels | 4 |
| Power Source | Battery Powered |
| Product Dimensions | 9.06 x 7.09 x 2.76 inches |
| Signal-to-Noise Ratio | 70 dB |
| UPC | 723800422475 |

## Product Details

- **Brand:** Kstpower
- **Color:** silver
- **Connectivity Technology:** Auxiliary
- **Connector Type:** 3.5 mm Jack
- **Included Components:** amplifier, battery, warranty card
- **Model Name:** F999B
- **Polar Pattern:** Omnidirectional
- **Recommended Uses For Product:** Investigation, Surveillance
- **Special Feature:** 3.5mm jack

## Images

![New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years) - Image 1](https://m.media-amazon.com/images/I/41EJz3KuvPL.jpg)
![New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years) - Image 2](https://m.media-amazon.com/images/I/516u180BZNL.jpg)
![New F999B Super Sensitive Listen Thru-wall Contact/probe Microphone Amplifier System (Warranty period of five years) - Image 3](https://m.media-amazon.com/images/I/51zzr01BIIL.jpg)

## Questions & Answers

**Q: can this be used to listed to heartbeat like a stethescope?**
A: Don't fit

**Q: can it record?**
A: No Unfortunately

**Q: how come i was sent a 929 when a f999b is what i should have gotten, all over this  page says f999b,invoice says f999b, it dosnt seem fair**
A: As some one who just got fired from Amazon I think you get a refund and buy it at any place as long as its not Amazon.

**Q: How far can you be from the microphone and still hear?**
A: Never worked, and the cost to send it back, and paperwork, is understandably why they can sell defective products, and not have to worry about refunds, or merchandise returns. Totally Dissatisfied

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great Basic Device
*by A***N on January 2, 2019*

Reading others views here, I thought I would add my own opinion. Definitely a Chinese manufacture, and quality is so-so. Packaging and case quality are frankly horrible. That said, I am loving this device. Do not try to hold the probe manually; you cannot keep it still enough for decent signal. Nor can you tape to wall firmly enough. Find or create a flat surface to adjoin the wall - such as a large, flat book. Then find something nonmetallic and HEAVY to press against the fixture to create non-moving firm contact. The sound quality isn't what you would get from a mic inside the target area - but it is VERY close. I use an Olympus LS-P2 recorder that has two 3.5 openings - one for external mic and the other for a standard headphone. I tried buying a cheaper Olympus MP3 recorder for dedicated use with this mic, but it didn't process the incoming signal well; so you really have to get a decent recording unit assuming you do intend to connect the unit to a digital recorder. The unit also has several ports - FM transmitter (which I don't use), DC Charging port, Mic (for wall probe), REC - direct connection to your digital recorder and EAR - for headphones. So you can monitor the recording either through the device or through your recorder. As far as the 'do not overcharge' message - Ok, that's a bit unusual, but I just recharge when I am on hand to monitor it occasionally; it's probably not something you want to run off and leave. When the light turns green, it's done and you can unplug - not a big deal IMO and certainly not a dealbreaker or anything justifying less stars or a neg review. By the way the battery life is great. I had to leave this on for about 8 hours unattended and the unit worked very well. My advice is shop around. As good as this is, it is clearliy 80s/90s tech; it's enough for my use, but there are probably better things out there albeit more expensive. $105 for this kit is completely justifiable.

### ⭐⭐⭐⭐ product critique
*by D***N on April 18, 2021*

satisfied

### ⭐ Piece of crap doesn't work at all don't buy
*by A***R on March 25, 2022*

Doesn't work a clear ripoff don't buy from this company or seller

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*Product available on Desertcart Kenya*
*Store origin: KE*
*Last updated: 2026-02-22*