If you are looking for a high performance trolley with an added safety feature, the ZLP Torpedo is it. It is made of stainless steel side plates and features hardened stainless wheels. Each wheel is equipped with two ball bearings giving it a faster, smoother, cooler ride. This helps ensure peak performance and extended life. The clip-in slot allows for the use of 3 carabiners to attach accessories such as a handle, seat, or harness. There is also a clip-in slot to attach a carabiner as an added safety back-up feature. The bottom of the trolley has an open design making the installation/removal of it as easy as clipping/unclipping a carabiner. Designed for cable up to 1/2" in diameter and speeds in excess of 100 MPH.