$14 per set. A set includes both sides (male and female). $15 per laser engraved set. First introduced in 2010 on the "54", Side Effects are our axle system that allow for easily swapping out the hub to change the weight and the look of your yoyo. For models that use this system, the Side Effects are interchangeable: any set of Side Effect works on any Side Effect compatible yoyo. The compatible yoyos are listed below and they include a few from other brands that licensed our technology. NQP means "Not Quite Perfect" visually, but they work perfectly. Full details here: https://onedropyoyos.com/side-effects/
