Each rack, 1/4", 3/8", or 1/2" drive, has 14 nubs which will hold most sets of sockets. These nubs, in combination with the urethane material its made from, is the other reason why we swear by this product. Lets break it down.|
1. There is a "rib" encircling the end of each nub. It makes for a very tight fit when initially pressing the socket on. Once the socket is on the nub this rib fills the pocket just inside of the socket keeping it firmly in place.
2. The urethane material isn't affected by chemicals, is incredibly durable against tearing or cutting, and has outstanding wear properties to provide a long life of holding sockets securely in place.