Easy to install/use. I purchased 1 set. This consist of 2 gel packs and, what I call the cover. 4.3 inches in length and 2.2 inches wide, tapering to 2 inches at the heel. You can purchase and add as many sets as you may need for your comfort level. These work, giving comfort to the heel area due to Plantar Fasciitis. I would start with 1 set and add more as needed.