Core Bit Extension 12" Length - Extension for Core Drill Motors 1-1/4-7 Thread - Concrete Core Drilling Extension 12"Core Bit Extension 12" Length 1 1 4" 7 Thread Core Drilling Extension Adapter TE712 Core Drill Extension Model Used for concrete core drill bits with 1 4" 7 thread to be extended 12 in. 1 4" 7 Thread x 12" Length Wet Drilling Core Bits Core bit extension Compatible with Standard Core Drill Motor Shafts Compatible with Standard Wet Core Drill Bits Quality Heat Treated Steel Long Thread Durability Equipment Core Drill Motors Hilti Weka Shibuya Dr.