Does what it's supposed to; good quality and durability. I use them for my 5th wheel; Also, I park my road bike under the fifth wheel because I don't want my bike in my RV but still want to protect it from the elements; I attach my bike to the front chassis and then also use a block to secure the bike tire so it stays centered just under the front of my RV; it prevents my bike from rolling onto the sides of the van and being exposed to rain and sun; very strong for heavy fifth wheels/RVs; I originally bought cheap, lightweight plastic bottles from the store, but these rubber ones are more durable and have ribs on the bottom to keep them in place. I wouldn't prefer people to buy cheap plastic as I've seen them crushed/crumbled by RV tires at RV parks.