Climax Metals MC-03X20 Steel Set Screw Collar with M2 x 2.5" Set Screw, Metric, Black Oxide Plating, 3 mm Bore Size, 7 mm OD (Pack of 20) Effective on hard and soft shafts Cost effective collar design Easily installed where major disassembly would otherwise be required Tolerance: +.0005/+.0025 Black oxide provides some corrosion resistance