THESE ARE VERY SMALL!!! Please be sure it will work for you, so I don't receive anymore issues them being too small. Thanks! This clasp is: 4.5mm diameter X 15.5mm, 5mm Spring Ring clasp 3/16" X 5/8" This will add 1/2" to items a dime coin is 17.5mmItem 154477975818 comes with 6mm spring ring In our opinion, suitable for chains up to 25grams. You be the judge for yourself. No hassle returns. It is strong enough to hold one side & slide all around the Nickel without it even starting to come apart. Clasp WILL be slightly attracted to magnet, as will other clasps. Their internal springs are steel. Rest assured these are 14k Gold FILLED 1/20 NOT responsible for any damage or losses due to clasp failure. USE AT YOUR OWN RISK if you use a PACEMAKER, INSULIN PUMP, OR DEFIBRILLATOR etc...Thanks Weight: 0.60grams DO NOT clean Magnetic Claps in ULTRASONIC cleaners as it will reduce the strength of the magnets.