1,Material: optical glass 2,Surface: spherical 3,Specifications: 20-300mm 4,Structure: plano-convex, plano-concave,biconvex.. 1, About us--Established in 1997, has been manufacturing the precise optical lenses for 15years. --With elegant environment of the garden type factory district, the advanced modern manufacturing machinery and testing equipment. --Having a strong development team consisting ...