... replaces an old one. It also acts as a stabilizer for drill bit. Reaming shells (with double ... . Size Available: "Q" Series: AQ, BQ, NQ, HQ, PQ (Front end & Back end Type) T Series: T36, T46, T56, ... T66, T76, T86 WF Series: HWF, PWF, SWF, UWF, ... AWT, BWT, NWT, HWT (Single Tube/Double Tube) WG Series: EWG, AWG, BWG, NWG, HWG (Single Tube/Double Tube ...