Volumetric Air Sampler (14407) samples air with the smooth, constant flow of a Rotary Carbon Vane. Oil-less operation with only one moving part requires very little maintenance. Regulator has a locked-in operating range of 3-20 lpm. Pump weighs less than 10 lbs. Diaphragm Pump (32451) samples air with lower-cost diaphragm operation. Flow rate: 3-18 lpm. Both pumps include rubber feet for stability, 5 ft. of clear tubing, adjustable aluminum stand and locking regulator. Stand adjusts from 1 ft. to 5 ft. high.