Snaps onto the handle of one of these large dog retractable leashes and provides a hook for affixing one of those little waste-bag holders, or something else. Edit 2013-08-16: Beefed up the strength of the hook part since my first one broke off too easily.3D-print without supports or brim. There are two versions: one is easier to slip onto the handle, while the other one requires more bending but holds more firmly. Slip onto the handle at the lowest point, by passing the handle through the gap, then turn to point the clip down, outside the leash handle. Slip the waste bag holder over the hook.