The Bel-Art Scienceware 199350000 clear polycarbonate flow indicator provides immediate visual indication of the flow rate and direction of water and other liquids. The indicator has a nylon ball housed in clear polycarbonate housing that rotates in a circular channel during flow. An arrow indicates direction. Continuity and relative flow rate are indicated by the speed of the ball's rotation. The indicator requires a minimum water flow rate of 100mL per minute in a horizontal position and 140mL per minute in a vertical position and has an upper flow limit in excess of 1 liter/minute. The maximum working pressure is 10 psig (pounds per square inch gauge ) or 69 kN/m2 (kilonewtons per meter squared). The polycarbonate indicator is 30 x 57mm (11/5 x 2-1/4 inches) (H x W) and has two 23mm (0.9") tube extensions to accept 6.4mm (1/4") to 9.5mm (3/8") inside diameter (I.D.) tubing. Bel-Art Products manufactures scientific products, including labware, testing equipment, and safety supplies, under the Bel-Art and Scienceware brands. The company, founded in 1946, is headquartered in Wayne, NJ..