ES # 160 VUV-UV Coating applied to a custom OAP per ThorLabs standard Part #: MPD129-P01: 25.4 mm diameter, 90 degree OAP, 50.8 mm RFL per MPD129-P01, with standard anodization/markings.
Note: The Coating clear Aperture would be 90% minimum. There may be some coating blow-bye onto the Anodized side finishes.