K-T type 27 depressed center wheels with 5/8"-11 hub. They are made with resin bond and are fully reinforced with fiberglass for safety at high speeds. Wheels are two-ply fiberglass reinforced for maximum strength. K-T wheels have a balanced design for long life, efficiency and safety in grinding jobs. Wheel size 4-1/2 x 1/4 Arbor 5/8 - 11. Type 27 Maximum RPM 13,300.