Please be sure you have an understanding of just how small they are.

Stronger and larger are https://www.ebay.com/itm/265820941014

This clasp is:    

• 4.5mm diameter X 22.5mm overall including 5mm Spring Rings
  3/16" X 7/8"  adds 20mm length
           a nickel coin is 21mm
  
  
• 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 rings WILL be slightly attracted to magnet, as will other clasps.
  Their internal springs are steel. Rest assured these are solid Sterling Silver
  
  
• 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