Fresnel Lens Magnifier, 200x200mm, Focal Length 210mm, Acrylic Lens (not Glass), for Physics Classroom, Solar Heating, Magnifiying, Fire Starter. (Focal Length 210mm)

I got this for fire starting in a pinch. With full midday sun, I had flame in about 20 seconds, not with paper or special kindling, just dry wood. Super focused and HOT!!!

Look, outside of maybe some very niche technical applications, the only thing you would buy this for is to set stuff on fire by harnessing the limitless power of our sun. I have a six-year-old boy, and this is a perfect time for some destructive play masquerading as STEM education! I have confirmed this lens is a properly made Fresnel lens, but haven't yet been able to actually execute on our pyromaniac plans because it's been so rainy and cloudy these past couple weeks.

The product came very clean and un scratched. It works well to burn easy combustible such as toilet paper or a paper towel. However, the focal point for the sunlight focus is more of a rectangle rather than a small dot, making the concentration of sunlight slightly less efficient. Overall a great product.

We are having just too much fun with this. Not only is it a great learning tool for the kid it shows how powerful the sun is. It came packaged nicely and although a bit smaller than I expected it's a nice lens.