Unlike spring-activated cord locks, KnotBone Cord Lock #3 has no moving parts. Its simple design allows you to secure the ends of pull cords of all kinds to the exact tension you need, and keeping them locked in place until you release it. To use, simply thread both ends of your cord through the Cord Lock #3s closed end, pull to the desired tension, wrap and lock. (For a loose cinch, just slide the KnotBone Cord Lock #3 to the position you want without wrapping—it holds a natural grip on the cord). Fits cords of approx. 2.4mm. Package of four.