TURNING TOOL HSS insert Boyer-Schultz No. 3/4 shank DUAL Rollers support – USA. Complete Ready to Use with Rollers & Bit! Shank 3/4 x 1 3/8. OA size of Head 3 1/2 long x 2 1/2 x 3. OLT indicates for L = Left hand turning rev. Bit size 3/8 Square. Thru hole 3/8″ (hole inside head is 5/8″). SEE ALL PICTURES – sizes approx.