Rub collar for 3/4" Arbor only, #980, (D) diameter 3-1/2, (D) bore 1/2 & 3/4, (b) Cutting height 1/2, (r), radius 1/4, C 7/8, optional rub collar c-006, 980 carbide Tipped 3-Wing raised panel Back cutter with ball bearing rub collar 1/4 radius x 3-1/2 dia x 1/2 x 1/2 & 3/4 bore.