1.It isbased of theguide screw clamping ,added elongated work driving arm and eccentric locking mechanism,that make the operation simple,efficient and labor-saving. 2.It is one of the main attachments for drilling machine .Easy to operate ,steady and reliable.ModelWidth of jaw (mm)Height of jaw (mm)Max.opening (mm)G.W./N.W (kg)Packing volume (cm)Packing shape135KZ1354814530/28 2sets/carton43×25×29Carton180KZ1805822529/2755×27×17Carton