Leashing yourself to your skis in the backcountry has benefits and drawbacks. If you are prone to yard sales and subsequent difficulty finding your skis, it can be a good idea to tie yourself in. If you are prone to getting caught in avalanches and swimming for your life, the last thing you need is to be anchored to anything that could pull you down. However if you end up resort skiing from time to time, the benefits are clearer: they are typically required by ski patrol who are keen to avoid untargeted missiles on their watch (targeted ones are usually banned at a higher jurisdiction).
The Dynafit Guide Leash is especially designed for the Speed Radical and Speed Turn bindings, which both happen to come with a set. If you need a replacement or want to fit another binding with leashes, give these a look. They have a detachable clip built into the line that lets you clip in and out easily. Weight is 18 grams (0.4 ounces) each. Sold in pairs.