...The parallel spring snap "S" is a versatile fastener suitable for all applications, equipped with high-quality bronze wire springs, double action, in an S shape, for smooth operation and maximum durability. Waterproof, it is particularly suitable for items such as jackets, anoraks, and ski or motorcycle outfits. Note: The installation of these snaps from the Prym Fashion brand is only guaranteed when using the installation set from the same brand with a manual press.