FIRM FLEX DUAL DRIVE UJ ADAPTER SET. Includes: 1/4” Spring Loaded Universal Joint adapter‐ Dual drive 1/4??. Sq x 11mm Hex3/8” Spring Loaded Universal Joint adapter ‐ Dual drive 3/8??. Sq x 17mm Hex1/2” Spring Loaded Universal Joint adapter ‐ Dual drive 1/2??.