Classic bindings come in three types: the SNS Pilot, SNS Profil/Propulse (the Propulse is the new version of the Profil), and NNN/NIS. Because classic skiing requires a more flexible binding, classic bindings are typically softer than skate bindings, and are available in both automatic and manual step-in models. As always, you should pay close attention to compatibility; Atomic and Salomon use the SNS system, while everything else is compatible with NNN (New Nordic Norm) binding, which can be mounted directly to the ski or to a factory-installed NIS (Nordic Integrated System) plate, allowing for easy, screw-free mounting and adjustment.
Almost any binding type can be used for racing or recreational skiing. The New SNS Propulse is one of the most popular choices, while NNN/NIS bindings and older Pilot bindings have strong followings too.
SNS Profil boots work with Profil/Propulse bindings, Pilot boots work with Pilot and Propulse bindings, and NNN boots only with NNN bindings.
SNS bindings will mount to any ski without an NIS plate, while NNN bindings can be mounted directly to the ski or to an NIS plate.