NOTE: All new V1 Rhino Sliders include the upgrade.
You only need to buy 1 Rhino Slider Upgrade per slider. It comes with everything necessary to upgrade BOTH of the outer rollers.
About a year ago, we ran into an early issue with some of our sliders, wherein the outer rollers would loosen a little bit and risk falling off. We addressed that quickly by sending out a free fix to everyone who reported a problem.
But because Rhino culture pressures us to keep innovating, we've engineered an even better solution and are releasing it as a very low-cost upgrade with free shipping for those who are experiencing issues or want to secure their outer rollers even more.