Review on 🖼️ ZWIN 2PCS Adjustable Picture Hanging Wire Kit - Heavy Duty Stainless Steel Wire for Mirrors & Pictures - 2m x 1.5mm - Supports Up to 20KG by Kelsey Brown

Works great. The rope is fixed by a load applied to the rope, pulled together by three miniature ball bearings. If you get curious and unscrew the bottom of the cylinder, the cable runs through it, that's it. Below is a spring and an adjustment tube. The tube has a flange at the top of the cylinder. Three miniature ball bearings are mounted in the flange part. They allow the cable to slide in or out (shorten or lengthen) when you press on it. When the tube is released, the bearings tighten the cable holding it. If you're curious and unscrew the bottom, the bearings will fall out, the spring may fly out, and you'll have to buy a new one. There is no way to put it back together.