12” Core Drill Bit Extension 5/8” - 11 Male to 5/8” - 11 Female - 5/8"-11 12" LengthTE1112 Model Used for concrete core drill bits with 5 8 11 thread to be extended 12 in. & their multiples. 5 8" 11 12"Length Can fit our concrete core bits with diameters smaller than 2" 5 8 11 female to 5 8 11 male Core bit extension Can fit concrete diamond core bits and all other core bits with 5 8 11 thread Can fit all other diamond core bits with 5 8 11 thread Dry Core Bits Adapter 12" Length