This rail clamps to your Beeman Underlever 1357, 1358, 1359 or Commodore pressure tube to securely add three 2 inch long 1913 Picatinny accessory rails. One on the bottom and one on each side. This will allow you to mount a bipod, laser, light etc. Made in Houston, TX USA by a veteran-owned business using an advanced selective laser sintering (SLS) process and covered by a lifetime warranty. We use three socket head cap screws and nuts to clamp the whole getup to the Underlever air tube. It locks firmly by clamping to the tube and engaging the barrel shroud.