Spey casting requires a lot of circular motion which tends to twist line. On many spey setups with mono filament shooting line after fishing through a run or two your line has so many twists in it that it ends up tangling on itself going out the guides just about every cast. This makes casting an absolute nightmare. To combat this the anti revolution spey swivel was developed here in shop and then adopted by Rio. The anti revolution spey swivel will keep your lines untwisted and allow for smooth easy casts. We can always improve our casting but we don't need our equipment working against us.