Stultz Triple Jack - a heavy duty screw jack that is 10" round with two 3/8" steel plates and three 1" fine threaded rods; each rod is 12" long. Rods are grade B7 with a 125k psi tensile strength. Ideal for center posts. Made in the USA.
Not rated. Weight ratings are based on capacity of the steel gauge, but there is no testing or engineered stamp available. A structural engineer should determine what is needed for a project, or use Nortek Levelers (see below), which have been tested/rated. Note: Always consult with an engineer for the right jack. Also: it takes years for the logs to settle, which means that it will take time for the jack to be lowered to a point where it will not be seen in the room.