Concord Blades CONV-WDB_X Core Bit Adapter 1-1/4"-7 (M) to 5/8"-11 (F) for 7 to 14-Inch Core Bits Male Thread Size 1-1/4 Inch-7mm Female Thread Size 5/8 Inch -11mm for use with 6" to 14" wet core bits that have the 1-1/4"-7 female threaded