This clasp is often called a hidden clasp
because when the watch band is closed the only portions of the clasp that show
are the buttons.  Because of this “invisible” clasp, the butterfly clasp is a
very popular watch band clasp.  Butterfly clasps are great for metal watch bands. 
The clasp is attached to the band by a tube with pins on each side of the band. 
The push buttons add an extra level of security to this watch band because the
clasp cannot open until the buttons have been pushed in.  To determine the size
clasp that you need, you measure the tube length. 

Made of stainless steel

Length: 37.7 mm

Width: 7.95 mm

Tube size: 4.0 mm

These replacement clasps are for metal
bands

Known as hidden clasps because only the
push buttons can be seen when it is completely closed

The top two butterfly “wing” sections fold
down onto the bottom portion and meet in the middle

The top portions are half the length of
the bottom portion

The push buttons are used to release the
inner catch and open the clasp

Related Products

These stainless steel butterfly clasps with push buttons are great for any watchmakers or jewelers workbench because they allow you to easily replace a watch band clasp & give your metal watch band a custom look.  This clasp hides behind the watch band.