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 specification cs8; paint all ground surfaces to ppe ss2; o/a dim. Inside dia. 141.0 metric , 141.5 metric , outside dia. 144.5 metric , 145.0 metric
