Keyless Chucks Key Holders Chucks Testing and approvals: Complies with OSHA and UL requirements -Price is for 1 Each. Model Code Model Description AAChuck Size:1/2 in, Includes:Chuck Key, Thread - TPI or Pitch:1/2 in - 20, Type:Industrial Drill Chuck ABChuck Size:3/8 in, Thread - TPI or Pitch:3/8 in - 24, Type:Cordless Drill Chuck ACType:Key Holder, Used With:1/4 in. Chuck Keys ADType:Key Holder, Used With:3/4 in. Chuck Keys AEType:Key Holder, Used With:3/8 & 1/2 in Chuck Keys.