Andersen trailer Jack blocks Paid $220. Used once. Built-in magnets instantly attach to the jack, so there is no need to double-check and adjust each jack block A 2-1/2" recessed post hole works great with post jacks Stackable for extra height (no more than 2) Each 4" Trailer Jack Block is rated to up to 30,000 lb or 20,000 lb when double-stacked Top of the jack block includes a 9-1/8" diameter recessed pad and a 2-1/2" recessed post hole for post jacks Ideal for heavier trailers that need maximum support Compact profile reduces jack extension for faster setup Made in the USA