... shells (with double pads or three pads) are suitable to use in all formation conditions ranging from broken and abrasive to ... physically longer than the standard type, it is necessary to use an appropriate inner tube extension in order to compensate for ... . Size Available: "Q" Series: AQ, BQ, NQ, HQ, PQ (Front end & Back end Type) T Series: T36, T46, T56, T66, T76, T86 WF ...