Universal Replacement Pump Sleeves - Multi ColorThe phrase no pain, no gain is a thing of the past with this set of two Universal Replacement Pump Sleeves. These durable penis pump sleeves slip over the bottom of your penis pump cylinder to add much needed comfort without breaking your airtight seal. Penis pumping works by using suction to create an airtight seal around your penis. Pumping up the air in the cylinder leads to increased pressure and blood flow to your penis. In the short term, this