*Material:Bk7,fused silica,CaF2,MgF2,BaF2,ZnSe infrared optical crystals. *Focal�length:+/-1% *Length�tolerance:+0.0 - -0.1mm *Width�tolerance:+0.0 - -0.1mm *Center�thickness�tolerance:+/-0.1mm *Surface�Figure:lambda/2 at 633nm on plano side *Surface�quality:60-40�stratch/dig *Clear�Apenture>90% *Chamfer:0.25mm at 45 degree typical *Coating:optional.