The Sonic Signal produces a very loud down range boom when launched. It is an excellent wildlife signaling round. Much louder than 12 Ga. Bird bombs. These are complete rounds ready to launch, loaded in CNC machined aluminum casings and fully re-loadable with the 37MM Reloading  Kits.  With each 3 Round Pack you receive 3 rounds loaded in 3 aluminum casings. The casings alone are valued at $20 a piece when sold separately. Hang on and do not discard them!