The DuoStand Ends let you upgrade your DuoStand Gen 1 to make it even more useful. The Ends feature grippy rubber caps that widen the DuoStand's base of support and add friction, both of which boost stability. They're also height-adjustable, so you can switch out your tires but keep your stand (for example, when installing winter tires).
The DuoStand Ends are included with the DuoStand Gen 2. They're available as replacement parts when yours are lost or worn.