"Material: Optical Glass Class 1 Grade B per MIL-G-174A; Finish: Surfaces marked ""P"" polished, all others ground; Anti-reflection coating: Multi-layer to MIL-C-675 PPE Spec CS8; Paint: All ground surfaces to PPE SS2; Dimensions: Inside diameter minimum 141.0 metric, maximum 141.5 metric; Outside diameter minimum 144.5 metric, maximum 145.0 metric."