Alvord Polk 128-0 Cobalt Steel Chucking Reamer, Straight Flute, Round Shank, Uncoated Finish, Size: 11/32 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) Round shank tools are cylindrical and should be held in a good-quality toolholder in order to prevent the reamer from slipping in high torque applications, which can cause tool freeze, loss of accuracy, and tool damage Uncoated (bright) tools have no finish or coating. They are a good choice for general purpose applications Cobalt steel is used for tough machining applications and on materials such as cast iron, cast steel and heat-treated steel. Cobalt steel resists abrasion and high cutting temperatures and has higher feed rates compared to high-speed steel