This is a used Benelli M3 Convertible shotgun.
The M3 Convertible is a no-nonsense shotgun that military and police all over the world depend on. This shotgun can be quickly changed from a fast cycling semi-auto for conventional loads to a manual pump action for low energy special purpose loads such as gas, beanbag and rubber bullet loads. For semi-auto action, merely rotate the selector ring 1/4 turn, push the forend forward and release the selector, to switch back to pump action simply reverse the procedure by pulling back after the selector ring is rotated to lock the forend to the action bars.
(Option two) To change between semi-auto and pump action simply rotate the selector ring at the front of the forend 1/4 turn then push forward to change from pump action to semi-auto or pull back to switch from semi-auto to pump action and then release the selector.
The M3 Convertible is available with matte black synthetic stocks, fully adjustable ghost-ring aperture rear sights and military style fixed-blade front sights. If your life depends on it, then depend on a Benelli.