The Mp-40 SMG was designed by Nazi Germany and was used heavily during WW2, this airsoft replica is spring action, just cock back the top slide and the M40 is ready to go. It's fast, clean, inexpensive and easily maintained. The gun does not require any gas or batteries to operate, it's ready for action right out of the box. If you're looking for a fun, reliable airsoft gun that looks and performs great, then look no further. You're bound to have a blast with this gun in your next backyard airsoft skirmish.