This bright red paddlewheel flow Indicator is made of polystyrene and indicates liquid or gas flow from 5ml per second to 95ml per second. The clear outer case allows for unobstructed view of the wheel which spins freely with flow. It is not for use with corrosive fluids or temperatures over 122°F (50°C). It can be used to connect tubing with internal dimensions of 3/8 to 9/16 inch (10-14mm). Dimensions (L x W x H): 3.5 x 0.625 x 1.625 inch. Per each; 5/Case. Dynalon® #: 227145.