FAST & EFFICENT MORTAR REMOVAL - Eat old mortar out fast with high cutting performance and long life. PREMIUM DIAMOND CONCENTRATION - Higher levels of diamond concentration than standard blades give the best performance to cost per cut. WET OR DRY - Use wet or dry for mortar removal, grout repair or preparing masonry and concrete surfaces. SPECIFICATIONS - 4 1/2" X .375" wide, have a 7/8" arbor with a 5/8" bushing and will work with most hand-held grinders and circular saws. The maximum safe operating speed is 13,500 rpm. LIFETIME WARRANTY - All Delta Diamond Products, Inc Diamond Blades, Coring Bits, Hole Saws and Grinding Wheels include a lifetime warranty against warping, cracking, and material defects. If any diamond tool (being used under its intended use with at least 50% wear left) fails to cut or work properly, or if the bond between the diamond segment and the steel core becomes separated at any time, the diamond tool will be replaced.