4 in Round Infrared Window Crystal Insert Size 100mm dia Viewing Aperture Size 93mm dia Viewing Aperture Area 6794 sq mm Window Thickness 4 mm NEMA Rating 12 3 IP Rating 65 Gasket Maximum Temperature 250 Degrees C (482 Degrees F) Body Maximum Temperature 659 Degrees C (1218 Degrees F) Optic Maximum Temperature 1400 Degrees C (2552 Degrees F) Voltage Range Unlimited Components Cover IR Window Body Material Aluminum Includes Access Key Drilling Template Fixing Screws