98mm Convolute X grade Phenolilc Liner and Kraft paper Casting Tube - Casting tube ID is 3.225".
These heavy duty liner tubes stand up to heat and pressure far better than spiral kraft phenolic liners and are a step above the LE grade. They use high quality kraft paper casting tubes and come in random lengths between 46" and 49". They will only fit hardware made from tubing with a 3.5" ID.
X grade is shown on bottom.