Belt 397t (for longer boom 295mm all-belt-drive). Special bulk purchase straight from the manufacturer. Will also suit 450 SE and 450 XL (extended boom uprade etc) Trex 397 teeth (397mm long). Same as Align replacement part HT1003. Made from polyurethane and Kevlar cord. Smoother and more slippery than rubber belts, with good tooth strength. Stock has just arrived, 13/02/07 and ready to ship.