Bore Hole Stabilizers are special thick walled drill collars subs that are placed in a BHA to force the drill collars to rotate at or near the center of the borehole. Stabilizers have blades or rolling cutters that protrude from the sub wall into the annulus to near the borehole diameter. By keeping the drill collars at or near the center of the borehole the drill bit will drill on a nearly straight course projected by the center axis of the rigid BHA. The blades may be rotating or not. The rotating blades are shop repairable. Non-rotating blades can be repaired at drilling rig location. It is effective in drilling abrasive, hard rock formation. Stabilizers are used extensively to improve the straight hole drill capability of a BHA for both mud drilling operations and for air drilling operations.