For all of you would-be eco-friendly mad-scientists, this lens will create a wow factor for your students/learners like non-other! On a bright sunny day you can extract enough solar heat to burn a copper penny or see how long it takes to heat up a bowl of water! They are 6 3/8" x 8 3/4" or 16.5 x 22.5 cm. The background grid is 1/4" or about 0.5cm square. Wooden frame not included. Sold Individually.

Check out this lens in action below! 

Fresnel Lens - Melting Pennies