This clasp measures 30mm long by 13mm wide and has 2 holes, with room underneath to crimp wires, if desired. Each end has one tiny 2mm diamante in clear crystal in the centre of the butterfly.
This clasp is particularly good for sewing onto woven items HOWEVER note that the end of the clasp dips in with the wings of the butterfly - the thread may be noticeable unless you use a tiny turning bead in underneath. The needle passes easily through the holes at the ends - pass the needle in through one hole, along underneath the clasp, then out through the next hole, weave around your item a bit, then pass back through the clasp in the same manner. Do this about 5-6 times to secure your weaving to the clasp.
If you are using crimps, the wire pokes into a hole, and the crimp gets squashed on the inside back of the clasp. There is room there for this crimp to neatly sit underneath. The crimp them prevents the work from pulling out through the hole.
The closure works by lifting the little lever in the centre which threads through from one side to the other (See photos I don't think I explained that particularly well!) and once this lever is clipped into place, you know you won't lose your bracelet or necklace because it's nice and secure!