Torque Solution Fat Head Delrin Shift Knob is made from an aerospace polymer Delrin material. Delrin material is impervious to heat and cold. Making it an excellent choice for racing applications and for daily driving in hot and cold climates. These knobs are designed to fit reverse lockout style shifters and do not require an adapter or locking nut. It is also not slippery and will not rattle like some metal knobs do. The hole extends as deep as possible to give you the lowest possible installed height.