Ok so you love the look of ball chain but some of your customers don't get on with the tube clasps? Easy, simply use these to attach a lobster clasp. Pop the last ball in your ball chain into the cup, with a drop of strong glue, close the cover, and that's it - you can now attach a jump ring on one side and a jump ring with your choice of clasp to the other. 

These also work well as calottes, holding the final knot on your stringing cord. 

For 1.5mm ball chains, sold in packs of 10 pieces.