Micro 100 Boring Bar, manufacturer part number BB-2301200SG.
Specifications: Minimum Bore Diameter: 1/4 in (0.2500 in); Maximum Bore Depth: 1.2000 in; Shank Diameter: 5/16 in (0.3125 in); Overall Length: 2-1/2 in (2.5000 in); Hand Direction: Right; Neck Diameter: 0.1730 in; Centerline Offset: 0.0738 in; Face Dimension: 5/32 in (0.1560 in); Projection: 0.0570 in; Tooth Width: 0.2000 in; Split Length: 0.2200 in.
Coating/Finish: TiN. Unit of measure: Inch.