Mini Electric Drill Chuck 0.6-6mm With 5mm Steel Shaft Mount B12 Inner Hole Features: High precision screw thread and tapered hole. Strong impact resistance. Compatible with impact dril and different power electric drill. JT0 taper the biggest end of diameter: 6.350mm JT0 taper The smallest end of diameter: 5.800mm Outer diameter: 21.5mm Taper: 2 degrees 49 minutes 24.7 seconds Work with 0.6mm-6mm Drill,The maximum clamping 4.2mm. Connection size: JT0 (inner hole diameter is 5 mm)