The Rottefella NNN-BC Magnum binding is Rottefellas most burly back-country system intended and is designed for the hard pounding associated with off-trail skiing. Rottefellas Back Country bindings are especially designed to perform in difficult conditions, where durability and control count the most. Innovative technologies, like sturdy closing mechanisms and wide binding plates, contribute to the optimal combination of performance, durability and comfort, for demanding expeditions and long trips. The Rottefella NNN-BC Magnum binding fits all Rottefella NNN-BC soles but DOES NOT fit NNN Touring soles so look for the NNN-BC logo on your boot soles if you are uncertain. NNN-BC Magnum bindings offer a stronger and more secure boot to binding connection than the automatic binding so if youre serious about your off-trail skiing choose the NNN-BC Magnum for your skis. Like all NNN-BC bindings, the Magnum bindings are wider for more stability and stronger than regular NNN bindings to withstand the rigors of off trail skiing. The integrated "Steering ridges" ensure maximum ski control and the flat heel plate provides stability in off-trail situations. The Rottefella NNN-BC binding system is the only heavy-duty back-country system binding currently on the market and works with a wide range of boots from light touring boots to the Alpine Alaska Heat heated all leather back-country boot.