Great little snap (15mm) ideal for Strike Indicators.....we use these on our own indicators and have done so for many years. The yarn is contained within the small end of the snap and tied down. The Indicator is then attached to the fly line end loop. These snaps can be quite hard to find but we do have many in stock and they have been manufactured for us. Comes in pack of 25 in clear, resealable pack for your convenience.