For temporary or additional support under stairs, porches, decks, crawl spaces and heavy load areas.Perfect for remodeling projects. Fully adjustable jack posts come with double carriage nut and bolt for added strength and safety. All moving parts fit snugly to avoid lateral displacement, and the top and bottom plates are deeply embossed to mitigate movement and prevent dishing. *Compression load range is testing to the point of failure. Maximum loads are obtained at minimum extension. To determine safe or allowable loads, consult a licensed engineer.