Glass Viewport Introduction
Glass viewports are an economical, practical and common solution for vacuum observation ports.  Glass viewports are typically sealed to low expansion nickel-iron alloys or 300 series stainless steel metal sleeves using the latest in glass-to-metal bonding technology.  The material in MDC Precision glass viewports is Corning 7056 glass, the most commonly used vacuum window material in the industry. 
Specifications
•	Zero-length offers greater distortion-free view area
•	>90% Transmission from 360nm to 2300nm
•	CF and weld mount bakeable to 400°C, 10°C/Min gradient
•	ISO Kwik-Flange® and Large Flanges bakeable to 200°C, 10°C/Min gradient
•	Optional AR Coatings available
•	Viewport Type: Zero Profile Viewport
•	Flange Size / Type: DN 40 CF (2.75" OD)
•	Viewport Material: 7056 Glass
•	Flange Material: 304 Stainless Steel
•	Bolt Circle: 2.850"
•	Bolt hole diameter: 0.332"
•	# Bolt holes: 8
•	Vacuum Range: 1 X 10-10 mbar to 1 bar (UHV)
•	Temperature Range: -20 °C to 200 °C
•	Weight: 0.830 lbs