Groove pitch: 0.3mm Material: acrylic (pmma) Transmission: 92% (from 400-1100nm) Index of Refraction nd : 1.491 Operating Temperature (°C): 80 (Maximum) Fresnel lenses are most often used in light gathering applications, such as condenser systems or emitter/detector setups. Fresnel lenses can also be used as magnifiers or projection lenses. These lenses are also great for enlarging fine print in books, magazines, maps, telephone directories, recipes, etc. This can really be a great and creative gift to children as a toy and those who need visual aid. This Fresnel lens is also very good for experiments of gathering solar energy. Thanks to its large size, it usually can start a fire within seconds on a normal sunny day. I personally can use it to start melting an aluminum can around 45 seconds under sunshine. Try it your way to boil a bottle of water, start a camp fire, or build a water heat pipe, etc. - Link, user name & password for the 6 plans will be emailed to you.

• 56.90USD for 2PCS/Pack
• Size:280*280mm, Focal length:600mm, Thickness:2mm, Material:PMMA
• Visual Aid for education - Great for reading small text, DIY Solar Cooking, DIY Solar Heater, and DIY PROJECTION TV, For Scientific Research
• High light transmittance, High efficiency in focusing
• Lightweight, Flexible, Durable

56.90USD for 2PCS/Packsix seasons technology