Carmex Extension With Internal Coolant Bor - for Indexable Milling Holders - E20M10L130Carmex Extension with Internal Coolant Bore for Indexable Milling Holders (E20M10L130) is engineered for precise, efficient threading on CNC mills. This extension keeps your workflow streamlined by enabling strong, reliable threads in a single tool pass while delivering coolant directly to the cutting edge. Internal coolant bore: Delivers coolant through the extension to the cutting zone for improved heat management, chip control, and tool life.