SUS 304 WPB is a stainless steel spring material and is based on JIS standard. 
Because it has strength and is excellent 
in springiness, even when opening and closing the snaps many times with the replacement of the lure, the shape of the snap is also less likely to collapse. 
Furthermore, because there is strength, we need a little power to open and close the snap, but this is also a proof of durability.

Ultra Snap BassDay