The folding submachinegun is a perennial favorite of personnel who require high firepower in a concealable package. The foling SMG is designed so that it can be collapsed into a very compcat package which doesn't resemble a weapon, but can be brought into action relatively quickly.
To deploy the folding SMG, one simply unfolds it and inserts a magazine. In all other respects, it should be treated as an SMG. Referees may wish to impose a -1 to hit to reflect the folding SMG's rather poor ergonomics and rudimentary sights.