Continually changing air pressure improves circulation. Model D pump with 8 gauge Medicare vinyl pad (11 columns, 2.5in inflated with flaps). 115V AC, 60 Hz; pressure fixed at 100 mmHg. Air output: 4.5 liters; cycle time: 5 minutes. Unit is UL-listed, measures 8.5in x 4.25in x 3-5/8in, and weighs 3 lbs. Includes 10ft power cord. Weight capacity: 220 lbs. 1-year warranty on pump; 6-month on pad.