ULTIMATE PROTECTION - The LEORAY heavy duty Chock for Jack Caster Wheels not only spreads the weight load evenly and prevents jack wheel from rolling or sinking into soft ground, but also prevents sideways movement once your caravan is in its stationary position. It's indeed a perfect solution to your trailer tongue problems. EXTEND JACK WHEEL SERVICE LIFE - Place the Chock underneath to prevent your Jack Wheel from incurring any damage from mud, sand, oil and dirt in general. Drainage hole prevents rain from building up and causing rust damage. The jack wheel chock keeps your jack wheel clean and prolongs its service life. MADE TO LAST - Made from premium nitrile rubber material in one-piece molding, the chock is super heavy duty and reasonably resistant to oil, water, gasoline, propane and some hydraulic fluids. It will keep your Jack Wheel safe for years and years. ODORLESS & EASY TO STORE - Being treated with high temperature vulcanization, it is durable, odorless, nontoxic and endures extreme outdoor temperature. With a portable size of 6.6 in x 5 in x 1.38 in, the chock could be easily stored in your car. NO-RISK PURCHASE - Your satisfaction is our top priority which is why we make sure that every product you receive from us is made with high quality raw materials and is defect-free. Our jack wheel dock comes with unconditional 30-Day refund warranty. Do not hesitate to contact us if you need any help. The LEORAY Jack Caster Wheel Dock is a simple solution that will keep your wheel in good shape for years to come. Made from the toughest rubber on the market, this chock is designed to firmly keep your wheel in place and prevent any sinking or sideways movement from occurring. Never worry about damaging your jockey wheel again. This dock will protect your wheel from any sand or mud from getting into your wheel, all while being held firmly in place. With the added drainage hole at the base, you'll never have to worry about rain build up either!