9 3/8" Long Sds Plus Core Bit Adapter / Arbor Screws Into the 5/8-11 Female Threaded End Of Diamond Core Drill Bits And Not Only Holds The Diamond Cores But Also Extends The Depth Of Cut. this Sds Core Drill Bit Adapter Extension Comes With A Drift Key For Removing Tapered Masonry Tungsten Carbide Tipped Pilot Drills (not Included) from the sds core drill adapter The Pilot Drills Are Used To Start The Core Bits Off And then Removed from the sds core adapter Once The Diamond Core Bits Create A Groove that can hold themselves in place. SDS Plus Core Drill Adapter is Heat Treated for Heavy Duty Use.