4.0Mm Min Bore Guhring Boring/Profiling Lh System 104 Insert, .015Mm (T-Max) Offset, 12Mm Reach, Uncoated Left Hand, 0.25Mm Radius, Bright Uncoated Gt104.0837.025.12.40.L, Uncoated Type Gt104 Guhring Micro-Precision System 104 Carbide Stick Insert With 4Mm Quick Change Shank For Boring & Profiling. Guhring Series No. 25089 Order Code 4.023 Made In Germany, Guhring Part #9250890040230 Guhring Inc.