High quality GrandMfg® Domed Brass Oil level sight glass window.

It have 3D View the liquid inside of the equipements. Below pictures show the water in the domed brass sight glass. The domed vycor glass never age.Easy to maintain: Just screw out brass sight glass and clean the dirty.

Brass oil level sight glass plugs for air compressor
Gear reducers oil brass sight glass plug
Coolant overflow expansion tank liquid level sight glass
Surge tank sight glass
Material Body:   Brass
O-Ring: Viton,FKM,FPM,NBR, Aramid gasket and Copper seal
Glass Thickness: 2mm to 5 mm
Reflectors: Stainless Steel 304 Reflector
Glass Type: Natural Glass,Tempered Glass and Borosilicate Glass 
Resist Tempreature Range:-30'C to 120'C
Pressure Range:  5-10 Bar(0.5MPa to 1 MPa).
Thread type:NPT,NPTF,UNC,UNF,Metric and BSP(G thread)