The MojoGrip™ is a nitrile rubber sleeve that provides a better gripping surface, and extra thickness to the back of the pick.
The grips come with a Delrin® pick already in place. However, the best part of the MojoGrip™ is that the grip is separate from the pick. If you wear down or break your pick, just carefully slide the pick out of the grip and replace it with another pick.
Delrin® is a registered trademark of E.I. duPont de Nemours and Company. It’s a modern plastic that has a woody but warm sound. This material also goes by other names in the industry such as Tortex® and Gripp-X.