Hollow saws Hollow electric hammer drill is composed of a guided drill and a connecting rod. It can be fitted to various electric hammers as a boring tool for processing large holes. It is a novel tool for installation and decoration trades. 1, Hex shank Length: 90 100 110 120(mm) 2, Plus shank Length: 110 160 200 250 300 350 450 500 600 800 1000 1200(mm) 3, Max shank: Length: 110 160 200 250 300 350 450 500 600 800 1000 1200(mm) 4, Hex shank mode--II: Length: 110 160 200 250 300 350 450 500 600 800 1000 1200(mm)