An oil sight glass is installed in a tank or reservoir, to visually show the left capacity of the liquid inside the container. Aluminum Body, Organic Glass Organic glass is more clear and more transparent. Aluminum Body, Tempered Glass Aluminum body is not easy to wear and burst. Organic Body & Glass Organic body is lightweight but has strong bending strength. Features Male thread with an O-ring on the periphery, easy to install and well sealed the oil.The outside diameter of the oil level sight glasses with recessed hex design.Used widely to check the oil level of the pump in CNC, air compressor, hydraulic machine, speed reducer etc. Oil Cup Cap Oil Cup Cap Oil Cup Cap Oil Cup Cap Oil Cup Cap Buying Options Add to Cart Add to Cart Add to Cart Buying Options Customer Reviews — 5.0 out of 5 stars 2 4.4 out of 5 stars 3 5.0 out of 5 stars 1 — Price — no data $7.02$7.02 $8.59$8.59 $9.99$9.99 — no data Material Brass Nickel Plated Carbon Steel Brass Chrome-plated Carbon Steel Aluminium Type Spring Cap Spring Cap Push Button Needle Valve Screw-on Color Copper Silver Copper Silver Silver