These trailer jack blocks provide stable support for RVs, trailers, and fifth wheels on uneven or soft ground. Each block supports up to 6,000 lbs and is designed to fit round or square metal jack legs, trailer support wheels, or insertable legs. Made from durable PP material, they offer non-slip performance on surfaces like gravel, grass, sand, and snow. The 2-piece set can also be used as seats, motorcycle stands, or step ladders. Their compact stackable design makes them easy to transport and store for camping and travel.