Just bought a single pump one for $39.99 the twin pump costs $49.99. But you have to pump the foot pedal twice as many times (strange that!!!).. Works really well and repco guy said they had problems with the attachment thingie but fixed that about 12 months ago. you need to pump about 4-5 times per pound of pressure (1/2 as much for the two pump one (strange that). Great to have in the shed and will be used alot. cheers and beers