Alvord Polk 625-0 High-Speed Steel Bridge Reamer, Straight Flute, #4 Morse Taper Shank, Uncoated Finish, Size 1-3/8 Inch Straight flute reamers are recommended for general purpose reaming to make minor enlargements to existing holes with a very precise size and roundness Straight flute reamers are good for use in through or blind holes without interruptions such as keyways (through holes extend through the entire workpiece, while blind holes do not) The end of Morse taper shank tools (held in a toolholder) is tapered to ensure accurate alignment of the tool in its socket and is self-holding (friction between the tool and the tool-holder prevents slippage) Uncoated (bright) tools have no finish or coating. They are a good choice for general purpose applications High-speed steel is a common general purpose steel for cutting tools, is compatible with a variety of materials, and tends to be lower in price than cobalt steel or carbide