The clasp size is 17 x 30mm loop to loop. This one is really special! We bought out a vintage German Glass component that was designed by Karl Lagerfeld - well known, top designer for Chanel. It has the KL monogram which is very well known and has been in Vogue for years. We believe that this piece was originally designed for cuff links but we decided to set these in sterling silver single strand box clasps. You can put some Chanel Couture into your designs with these genuine Karl Lagerfeld monogramed sterling silver clasps. Get them while they last. What a find!!!!!!