The Andersen Trailer Jack Block provides fast and easy trailer stabilization. Attach the Trailer Jack Block to the pad and level. It's that easy. The Trailer Jack Block offers 5th wheel and RV stabilization, all while reducing stress on your jacks. The built-in magnets instantly attach to the jack, so there's no need to double-check and adjust each block.• Built-in magnets instantly attach to the jack• No need to double-check and adjust each jack block• 2-1/2" recessed post hole works great with post jacks• Stackable for extra height (no more than 2 blocks)Ratings and SpecsEach 8in Trailer Jack Block is rated to up to 8, 000 lbs or 1, 500 lbs when double-stacked12 diameter base, 10 diameter topTop of the jack block includes a 9-1/8 diameter recessed pad 2-1/2 recessed post hole for post jacksWeighs 5.3 lbsMade in the USACovered under lifetime warranty Built-in magnets instantly attach to the jack No need to double-check & adjust each block Each block is rated up to 8, 000 lbs. / 1, 500 lbs. when double-stacked | Andersen Hitches Trailer Jack Block - Single, 8 Inch Made in USA