Effective Protection: our jack wheel chocks prevent wheels from rolling or sinking on soft ground and sideways movement when the RV is stationary by distributing weight evenly; Better solution to trailer tongue problem, providing reliability and stability Reliable Material: our rubber caster wheel are made of rubber, extra heavy-duty, providing long-lasting protection for your jack caster; We used better quality materials, so the product has a long service life, and it is a for long-term protection of the wheel Product Size: our trailer wheel chock stabilizers are approximately 6.6 x 5 x 1.38 inches, designed for long-lasting outdoor conditions, guaranteeing safety; Trailer tongue jack wheel mount is suitable for 6-inch casters; With the base and wheel chock stabilizer of this travel trailer kit, you can park safely anywhere you want Extended Service Life: use our heavy duty wheel chock to help keep your jack wheel away from sand, oil, mud and dirt and extend its service life; This wheel chock features drainage holes to it can be used by anyone who values trailer wheel maintenance Wide Application: our trailer jack wheel can accommodate a variety of solid wheels on RV trailers, trailers, boat trailers, tent trailers, and campers; Enjoy wide compatibility and easy installation of different types and wheel sizes Colour:As Shown Material:rubber Package Contents: 1 set * trailer jack block Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.