Ultra-Fab Products 21-001060 Ultra Deluxe Chock and Lock Easy to use, one piece stabilizer chock collapses to just 1.5" Unique design eliminates front-to-back rocking motion Works by anchoring the opposing wheels of tandem axle trailers and fifth wheels. Lockable to prevent theft (padlock not included) E-Z grip handle creates better leverage Ultra-Fab Chock-N-Lock Deluxe Ultra Chock for Tandem Axles Enjoy greater comfort with Chock-N-Lock Patented device locks in stability to eliminate front to back movement when you're in your RV Locks the two wheels of the tandem trailer to render them motionless Effective on most trailers regardless of wheel spacing or ground surface