HHIP 4100-0040 Center Line Gage Set for 4", 6" and 8" Calipers

You will probably want to dedicate a set of calipers to these, as they do take a little time to attach and mount perfectly.

good accuracy, machining seems fine, works great, but awkward to install and reinstall as zero cant be checked while installed...

One tip is rounded off to one side, other than that they seem okay. Easy fix and still worth the money.

Looks like it will fit most calipers

Worked well and a great price.

Instalation is difficult and prone to inaccuracies due to the dual sets of setscrews. This is likely an attempt to make them adapt to different sizes and manufacturers. As precision is the purpose of this tool, it is largely self-defeating.

Quality is sub par for precision measuring use. Rough surface finish on jaws. The cutting of the slot for mounting is uneven. At least two lengths of set screws are used on the jaws. Having said that these are still a deal for the price. Make sure you drill two holes at know distance and then mount and use the center line gage set and verify it reads the same. It is possible and perhaps likely that the jaws will not mount parallel to one another the first time. This is another reason to mount to a purposed set of calipers then leave alone.

Fussy to put on, need to be dedicated to a caliper (no quick change), and you need to use a caliper with "ABSOLUTE ORIGIN" such as iGaging ABSOLUTE ORIGIN 0-6" Digital Electronic Caliper - IP54 Protection / Extreme Accuracy because you can't zero it out once you put these on, but once they're setup they work great.