Small Hole Boring Bars Catalogue Numbering System How Do Catalogue Numbers Work? Each character in our catalogue number signifies a specific trait of that product. Use the following key columns and corresponding images to easily identify which attributes apply. CSBM5210125R C S B M Series Type Bar Type Bar Style Designation Units Insert Shape (optional) M = Metric C C W S = Steel (with coolant) F G C = Carbide (with coolant) B O L Boring Bar Offset Boring Bar C P External Profiling Bar Q Chamfering Bar I R Internal Reverse Chamfer Threading Bar or Back Chamfer Bar M Offset Internal Grooving Bar S D8 widia.com