Those are called 'pump jacks'. The upper blue piece in the pic gets attached to the house in a 'V' pattern. This is supposed to control side-to-side movement. The lower blue piece with the black stirrup is the jack. You put your foot in the stirrup and pump. The platform will walk up and down the 4x4 risers. You need to jack both sides. I bought a set when I built my house. Tried to use them once, didn't have the bulls for it. Pretty scary if you're not used to it. They sold at our last garage sale.