... glasses, sight gauge, sight gage, oil level indicator, liquid sight glass, sight window, view ports, male thread ... material: aluminum, brass, PC, PPMA and steel Glass: Real glass 2 mm to 5 mm thickness. O Ring: Viton O rings ... Size: M10 to M42, 1/2 inch to 2 inch Thread Type: Meter thread, BSP, NPT Operate Temperature: -20 cent ...