What can I say about this that will convince you that this clasp and extender set is the best investment you would ever make for your expensive and costume jewelry.  The magnets are strong enough to hold extra heavy jewelry as well.  The extenders are a wonder.  You may use just one chain to extend the length, or two of the same length, or use one long chain and one shorter chain.  You can mix them up and do whatever you want with them to make them work for whatever you are wearing that evening or day.  They are also so very easy to put together.  There is no close up work, nor tools needed to attach them to your jewelry.  You will not make a mistake investing in this item.