Thermaltake AquaBay M1 CL-W0032 2U Liquid Level and Flow Indicator Can apply to Thermaltake Bigwater and other liquid cooling system Indicator can fit into the 5.25" drive bay in the case Connect temperature probe to tubing of 6.4 to 9.5 mm to inner diameter Transparent window has an indicator to show the level of liquid system Stylish front mounting plate is designed to attach the indicator within two 5.25" drive bays