“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.”—OneDrop YoYos

Spike Side Effects
3.2 grams

Ultra Light Side Effects
2.5 grams

Energy Dome Side Effects
3.5 grams