Product description Main Features: - Fits all sizes of Bi Metal hole saw diameters: 16-152mm (5/8"-6") - Fitted with 6.35mm (1/4") HSS4241 pilot drill - Quick release locking system - Including A2+A4 adapters A2 adaptor: 5/8-18UN, 11mm shank, 115mm overall length A4 adaptor: 1/2-20UN, 9.5mm shank, 95mm overall length - Professional tool for commercial or occasional use