Specialised and highly effective steel wiregate device, intended for use as a braking karabiner. Very hard wearing braking tool suitable for use with simple, stop descenders etc. Most effective on thin ropes (8mm - 9mm) or those of unusually low friction; perhaps occasionally 'snatchy' on thicker or older ropes. Safety is increased through the high friction, which comes into its own when heavy loads are carried, and also on larger pitches where rebelay failure below the caver may be a risk (see the Caving Technical Manual)
Most suitable for more experienced users; but also for anyone who is expecting to encounter 'fast' ropes!