20pcs Double Convex Optical Lens for Magnifier - 42mm Diameter Biconvex Plastic Lens for Magnification

Plastic, cheap, did not even use.

These lenses are perfect for making spotlights out of led lighting. They are meant to be used for magnifying glasses I'm guessing, but for my purposes they were perfect! For the sake of review I used one to magnify some of the items around my house and they work perfectly for their original purpose. But as mentioned, these are great for a lot of purposes.

I was super excited! My class was thrilled to hit the playground and inspect bugs. I wanted a glass lens that would be durable for my kids. Very disappointing.

A different reviewer mentioned that this lens is convex only on one side. At first thought they were correct, until I checked. If you hold them together, you can see that one side is very curved while the other is flatter but still definitely curved.These lenses are pretty high quality, considering they are made of plastic. With 20 lenses, you have enough for some cool optics experiments. They’re a little smaller in diameter than the inside of a TP tube; I haven’t tried, but I expect you could make some lens mounting and focusing equipment out of craft foam, pipe cleaners, and popsicle sticks. I ordered them because I have been wanting to try making a Flavia de Luce crucifix inspired by the Alan Bradley books. These are a bit large to be completely true to the books, but there are plenty of lenses for experimentation.