Material:                        BK7 Grade A optical glass

Dimension Tolerance:       +0.0, -0.2mm

Clear Aperture:               >80%

Deviation:                       180° ± 3 arc seconds

Flatness:                         l/4 on big surface, l/10 on other surfaces

Surface Quality:               60-40 scratch and dig

Wavefront Distortion:          l/2 @633nm

Bevel:                             0.2mm to 0.5mm