The hook is for 1/4" and 3/16" bungee cord;
It is maybe tight on a 1/4" cord and hard into the end of hook, you can stretch the cord to make it thinner and smear on some instant glue gel to keep it thin prior to cutting, or you can use a lighter to melt the end of the cord to make thinner and cut, The key is make sure the end is smooth and tight not loose

How to use:
1. Take the collar pass through the rope
2. Insert the cord into the base of the hook until it stops
3. Slide the collar onto the hook base until the prongs are forced down into the cord, holding it in place
4. At the same time, holding the collar in place