Features:This flow indicator is used to observe water flow speed of water cooling system, in case that pump stops working and causes overheat. Simple and practical, easy to install, small size and durable. Black impeller is convenient for observation, normally used in computer or other water cooling systems. G1/4inch thread is widely fit for most computer cooling tubes or connectors. 8 impellers design improves the cooling efficiency. Specifications:Material: POM + AcrylicOptional color: White, BlackThread: G1/4"Seal: Silicone ringLength: Approx. 77.5mm / 3.05inchWidth: Approx. 47.5mm / 1.87inchThickness: Approx. 19mm / 0.75inchWeight: Approx. 39g Package Included:1 x Water Flow Meter.Note:Please note that the grooves of the lid will be sent randomly, and make sure you will not mind before ordering.