Designed to fit between the tyres on a tandem axle caravan, motorhome, rv or trailer to stabilise the suspension, which eliminates sway, rocking, and other movement while parked. To install, you simply hold the chock between the tyre using the integrated handle, expand to conform with the tyres, hand tighten the nut on the tightening bolt, then finish using the included ratchet spanner. A padlock is also included to secure the chock in place. Made from heavy gauge steel with a corrosion resistant zinc plating. Suitable for dual axles with a tyre spacing up to 10 expanding dual axle metal stability chock padlock and keys ratchet spanner note these chocks do not replace brakes or wheel wedges to prevent the trailer or vehicle rolling.