DRY Diamond Core Bits - Monster Brand are designed to meet the demands of more and more core drilling applications right on the job sites. These high quality diamond core bits can be used both dry and wet on granite and concrete countertops. 1/4", 3/16", 3/8" and 1/2" bits are non-core bits. 5/8-11 arbor fits standard polishers and grinders. Maximum speed for the bits are 4500 RPM. Use water to cool down the bit is highly recommend to extend their lives.