Premium Pro-Grade Diamond Core Bits. Side diamond dots help prevent binding & slab cracking. Leaves flange clean & promotes fast coring. Standard 5/8" thread or use 21-600-A Adaptor to use with drills. 1-3/8" works for most plumbing fixtures. It is recommended to use water to extend the life of all diamond products. You can use a spray bottle with water. Other sizes available.Features:Premium Grade Diamond Core bitSintered diamondsStandard 5/8" threadUse 21-600-A adapter for drills (sold separately).