"Used these to finish 1.5mm round leather for a necklace and they were perfect. Added a JBB 21mm Gunmetal-Plated Brass Swivel S Hook Clasp and had just the look i wanted. So easy! Do use chain nose pliers (rather than a crimper) to "crimp" the center section for a less flattened and more professional look. Although i'm sure i read someone's tip (on another crimp end cap item) that for best results use chain nose pliers, i had to try using a crimper and was not thrilled with the result. Switched to chain nose pliers for the 2nd end and the results were perfect. Now i have to replace 1 end (lol). Just be a bit gentle for a perfect result. I've also been very pleased with the quality of all the JBB items i've used; thank you artbeads for offering JBB at an affordable price."