This clasp is:    

• 4.5mm diameter X 22mm, 6mm Spring Rings (pictured with 4.5mm)
  3/16" X 5/8"
           a dime coin is 17.5mm
  
  
• 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.
  
  
• Spring ring and other clasps WILL be slightly attracted to the magnet, as their internal springs are steel.
  Rest assured these are solid 14k
  
  
• NOT responsible for any losses due to clasp failure.
  
  
• USE AT YOUR OWN RISK if you use a PACEMAKER, INSULIN PUMP, OR DEFIBRILLATOR etc...Thanks