Keeps tractorless trailers leveled while being loaded or unloaded. Prevents accidents if wheel support collapses. Stabilizes vehicle against load shifts. 8" dia support pad. 8" wheels. 100 000 lbs. supporting capacity each and 40 000 lbs. lifting capacity. 1 year warranty. Recommended use in pairs. Lowered height: 39 1/2" . Raised height: 51" . Yellow.