FPW1423-2232 Features: -Firepower depressed center wheels are fully reinforced with resin bonded aluminum oxide to ensure safety at high speed and to increase bonding and impact strength.-Designed for use on air or electric powered right angle or vertical shaft grinders.-With hub.-4 1/2 in. x 1/4 in. x 5/8 in. -11NC Depressed Center Grinding Wheels, Type 27. Warranty: -90 day warranty on material and workmanship.