DeWalt DW5779B15 1 Inch x 12 Inch Cold Chisel 3/4 Inch Hex x 21/32 Inch Round Spline Shank (15 PK). Add versatility to your rotary hammer with a wide variety of specialty bits. DeWalt demolition hammer steel is made from hardened steel to reduce breakage and provide long life. For use with rotary hammers that accept 3/4-inch hex by 21/32-inch round shanks.