Multi-Threaded Self-Retaining U-Nuts, also known as Tapped Barrel U-Nuts, are primarily used in the automotive industry where extra strength is required. The strength of the tapped barrel u-nut is equal to the machine screw used. It allows single-wrench tightening of the thread assembly. In addition, some multi-threaded u-nuts are available in Free Spin or Prevailing Torque designs. This page displays Imperial Thread X Pitch Sizes from 1/4 x 20 - 10 x 32.