petzl micro traxion ultralight progress capture pulley petzl the micro traxion is an ultra-light (85 g), ultra-compact progress-capture pulley that is exceptionally efficient (91 %) thanks to its sealed ball bearings. the cam works on dirty or icy ropes and can be locked in open position for use as a pulley. diagrams for rope installation engraved on interior of pulley. designed for crevasse rescue, hauling, self-rescue and can be used as emergency ascender.