Rubber Gripper - ChiaoGoo
Help secure your interchangeable tip to cable connection by using these heart-shaped, rubber grippers. Take the "extra grippy" back side and wrap the gripper around the tip.
Use it with the tightening key to help get a good grip and tighten the screw connection.--
Rubber gripper 2" x 1.25" (5 x 3.2 cm)