The link opens for you to slide your charm on and then you close it. I was skeptical at first, but the link closed firmly and I did not have any issues for about the first month of daily wear. One day while in the car, I noticed the link was open and my charm was gone. Luckily the charm fell into my shirt and was caught in my bra. I panicked initially thinking I lost my new charm. When I tried to replace the charm, the link wouldn't close and was loose. I really wanted to like this, but it did not live up to expectations and almost cost me $$$ as I would have lost the pennant on it.
I have purchased several chains and charms and one link in the last year in which 3 necklaces broke and one link broke. The only pieces that didn't break were the Goddess pennant, my 888 Angel Number Charm and my Ankh of Isis Charm.
If you like a charm, I would recommend them. Anything else hasn't been durable enough to hold up more than 1 month of wearing it daily.