Rub collar for 3/4" Arbor only, #961, (D) diameter 2-5/8, (D) bore 1/2 & 3/4, (b) Cutting height 1, (r) radius 5/64, B1 5/8, optional rub collar c-015, c-028, 961 carbide Tipped 3-Wing triple flute 5/64 radius x 2-5/8 dia x 1 x 1/2 & 3/4 bore