Sir 0375 K11 Internal Threading Holder For Size 16 Laydown Threading Inserts Sir 0375 K11 Internal Threading Holder: Neck Diameter = 3/8 Inch With A 5/8" Round Shank Diameter Right Hand Boring Bar Internal Lay Down Threading Holder For Size 11 Inserts Meter Right Hand Boring Bar Internal Lay Down Threading Holder For Size 11 Inserts Tmx Toolmex Part #6-Sir-375-K11