Lightweight, but good for a medium weight necklace. One side nests inside the other side for a secure closure, without a super-strong magnet.
Really good product. It holds well. It looks good. And the ends 'find each other' when clasping it, like for a bracelet. Nice.
I have used this clasp on two anklets and it works great. Probably too obtrusive for very fine pieces but great for casual stuff.