Prevents damage to RV or trailer undercarriage from tail dragging and digging. Contacts ground when RV or trailer would drag or dig into ground. Drop forged caster for superior strength. Ultra strong metal wheels include roller bearing and .25” urethan on the outer edge. Swivel design to maximize effectiveness. Simple weld-on installation. 5” wheel diameter. Installed height is 7.25”. 2 per pack. 1-year warranty.