They cover the cutouts in your rim and — if you’re running a tube — they protect it from spoke heads and other sharp matter (okay, so maybe they have TWO jobs but they do them both really well.). PVC is great if you plan on only running tubes.
RABBIT cage titanium bottle cage bottle cage RABBIT cycles titanium moots NEW
Halo T2 rim 20'' 24'' 26'' 27.5/650b 29'' 36 hole & 32 hole
WIDEK Miffy Rabbit Bicycle Bell
12 Pcs Stainless Steel Springs & Clips,Guinea Pig Water Bottle, Rabbit Water Bot
RBRL Bike Kickstand, 18mm Hole Spacing Anti-slip Bike Stand, Height Adjustable Bike Side Stand, Aluminium Alloy Durable Bicycle Stand for 24"-29" Ebike/Mountain Bike
BV Adjustable Rear Mount Bicycle Bike Kickstand for 24" - 29" Mountain Bike/Road Bike/BMX/MTB (18mm (Hole Distance))