Rebuild kit for PAPAILIAS 150# NW50 weld pad style sight glasses feature a Tempered Borosilicae Glass lens and Expanded PTFE seal gasket.This Rebuild kit is supplied with the following parts:[Qty: 1] Lens: Tempered Borosilicae Glass Lens [≤500°F][Qty: 1] Seal Gasket: Expanded PTFE [≤500°F][Qty: 1] Inorganic Fiber Lens CushionsAll instruction must be read and understood thoroughly before attempting any installation, operation or maintenance. Failure to follow any instruction could possibly result in a malfunction of the sight glass and/or glass breakage with resulting sudden release of pressure causing serious personal injury and/or property damage.ALWAYS WEAR SAFETY GLASSES WHEN INSTALLING OR SERVICING OR OPERATING A SIGHT GLASS.