Superior Electric S3-TH1A 5/16" T-Handle Chuck Key Fits Bosch & Makita Drill Chucks D1: 20.6mm (0.811 inch), D3: 7.9mm (0.311 inch), L1: 85mm (3.35 inch) Works with many chucks including Bosch, DeWalt and Makita This part is compatible with: Superior Electric J3516A Well machined 5/16 inch (5.9mm) pilot shank chuck key