Bindings are the most complicated aspect of putting together a Nordic touring setup, primarily because boot/binding/ski compatibility can be tough to figure out. The three best Nordic touring binding options are a traditional 75mm three-pin binding, which is large, durable, and easy to use, SNS which is Salomon’s proprietary binding system, and the NNN BC (New Nordic Norm Backcountry) binding, which uses a small but strong clamp to secure your boot to the ski. Both of these options make it easy to control your skis, and are more rugged than standard Nordic skiing bindings. The 75mm three-pin is easy to repair but is too wide for groomed Nordic tracks, while the NNN BC is available in both automatic step-in and manual models, but requires compatible boots.
NNN BC bindings clamp around a metal bar in your boot's toe, while 75mm three-pin bindings use metal pins and a toe bail to secure boot to binding. SNS is similar to NNN except SNS uses a smaller bar and a modified binding plate with one large ridge.
75mm three-pin work with traditional 3-pin duckbill boots, while NNN BC bindings work with NNN BC-compatible boots (check product specs). SNS bindings require SNS boots and are not compatible with NNN.
Mount 75mm three-pins, SNS, and NNN BCs on any ski. It's not recommended to use these with a Nordic Integrated System (NIS) plate.