The jack is actually called "Trailer Jack" and it's brand is also called "Trailer Jack". It is a hand cranked jack designed to lift 7000 pounds and is capable of 8000 pounds while in static mode. It's advertised lift is 28" but I have had mine a few inches over the 28" advertised. It is made out of what appears to be galvanized square/tubular steel. Before using it, it needs to be lubricated via the zerk at the top of the jack. It has a large foot plate permanently attached to an inner tube which is removable but is designed to be semi permanent. The jack foot plate and tube can be removed and are held in place with a 1/2" lock pin. When traveling the jack foot plate is raised and held in place with the lock pin which also has a safety locking device. There are multiple foot plate heights/locations as the bottom tube has multiple pin locations which are used to change the height of the bottom tube. It is solid and appears to be well built. It comes with mounting hardware. No drilling and no welding required.
I also have a 3500 pound 12 volt electric jack (I believe it is a Stromberg model) with triangle mounting plate. It is virtually new. It was used not more than 5 times on our first trip. I upgraded the jack on my travel trailer to a 5000 pound.