The #4 Ascender is intended for litter raising and load hauling, where extra strength is required. Not for self belay by solo climbers.
Gibbs Ascenders are designed not to slip. They hold well on iced and muddy ropes. Their simple, durable construction makes them almost fool proof. They are easy to assemble on the rope yet will not come off unexpectedly. They can be rigged in all the standard methods for mechanical prussiks.
Assembly: Depress button on pin and pull pin out until cam swings free. Place Ascender on rope and align holes in cam and shell. Depress button and insert pin.