All Agilent ConFlat viewports come with clear hole flanges and are rated to below 10-11 torr. Zero Length Glass viewports can be baked out to 400°C and have an approximate transmission range of 0.32 to 2.7 microns.
Sapphire standard and zero length viewports can be baked to 450°C and have an approximate transmission range of 0.25 to 5.5 microns.