The quiver of one that can do it all. It's a concept many ski, boot, and binding manufacturers have been addressing for years. The idea being you have a ski that can handle a variety of conditions relatively well, a boot that is stiff enough to bang out resort laps—but has a walk mode to get some low-hanging fruit backcountry laps that is coupled with a binding that walks decently enough but isn't terrifying on ice and moguls.
Recently that unicorn has emerged, but sorting out which binding is compatible to the Anti Friction Device (AFD)—located on the sole of your ski boots and responsible for the release safety, is becoming ever more important. Especially if you bought a fresh new boot, but perhaps have an older binding lying around or nabbed something at a ski swap.
Many brands offer their own platforms such as Salomon and Atomic's Walk to Ride and Marker's Grip Walk, with most major alpine boot brands utilizing one or the other in their cross-over boots (i.e. alpine boots with a walk-mode). And while those labels originated with brands, the crux of it all is based on certifications—German ones, so the naming isn't catchy but rather incredibly linear and numerical to keep things in check albeit confusing.
Below are some terms that you should keep in mind when or after purchasing new boots or bindings. Think of this as a gear glossary, so you don't end up dropping in on a powder day at your resort and promptly eating it down the hill.
DIN: Is short for Deutsches Institut für Normung (German Institute for Standardization). It's a scale of release force settings for your ski bindings set by the Institute, yet is published by the International Organization for Standardization (ISO). Still with us? Good, here's where it gets interesting…
Release Value: The release value of a binding is often confused with DIN. Reason being: prior to the explosion in backcountry gear, alpine ski boots and ski bindings all got along on the same platform (ISO 5355). However, a release value doesn't have to be standardized. The definition of a release value in a binding relates to how much torque is required to release the boot from the binding. So unless you're using a strict alpine boot to alpine binding, you're release value isn't DIN. It's semantics, but without the standardization not all release values are created equal.
Walk to Ride: A Walk to Ride Boot has low-tech inserts (i.e. pin bindings such as a Dynafit) to accommodate tech touring bindings and can also fit into specifically certified alpine bindings. Walk to Ride Boots can only fit safely into Walk to Ride (WTR) or Multi-Norm Certified (MNC) bindings. So look for the WTR or MNC Stamp. A few examples are Salomon's STH2, Tracker, and Warden bindings.
Grip Walk: Similar to the Walk to Ride system, Grip Walk boots will not work with all traditional Alpine bindings, but will align with WTR, MNC, and Grip Walk certified systems. An example here would be the Head Kore1 (Grip Walk) boot with a Salomon Shift binding (MNC).
ISO 9523 – Compliant Touring Boots: These boots have the traditional touring rubber soles with a slight curve. They are true backcountry ski boots, but the 'complaint' description means that some touring boots (not all) can fit into a MNC alpine binding.
ISO 9523 –Non-Compliant Touring boots: These are most likely paired with a pin-tech binding. However, just because you're not hill-banging at the resort you might still be concerned with your release safety. If so, see below for more.
TUV: TÜVs provide inspection and product certification services. It stands for Technischer Überwachungsverein. To not get too hung up on this, TÜV certification in a tech bindings have become a status sought after as skiers continue to push the boundaries of what you can do with a pin binding. For example, the Marker Kingpin, Fritchsi Vipec, and Dynafit Radical 2.0 all have achieved TÜV certification for the DIN ISO 13992 standards—meaning they offer certified safety releases from the boot and binding, not just a release setting as noted previously.