Abstract: A seat post includes a tube having a stop secured in the middle portion. A pipe is slidably extended through the stop. A rod is secured to the pipe and has a seat cushion secured on top. A spring may bias the pad to engage with a stop of the tube and to cushion the rod. A bolt is threaded to the tube and engaged with the pad for adjusting the spring force of the pad and the spring against the pipe. A barrel is secured on the tube and one or more studs are engaged between the barrel and the rod for preventing the rod from rotating relative to the barrel.

Abstract: A rollerboard includes a tube having a front wheel secured to the bottom and having a handle. A bracket is pivotally coupled to the tube and has a lower portion pivotally coupled to a board for allowing the bracket to be folded relative to the board to a compact folded configuration. A beam has a lower portion pivotally coupled to the board and has an upper portion pivotally coupled to a bar at a pivot pin. The bar is pivotally coupled to the bracket. The pivot pin may be forced toward the bracket for securing the tube at the vertical position relative to the board.