Very robust steel, brass and aluminum build with a tough steel base. More durable than our standard MegaBOOM STS with the polycarbonate base. Package contains: MegaBOOM target system, Ballistic Bag, and valve tool. You supply an air source such as a bicycle floor pump, compressor, or dive tank. You provide a one to two liter soda or water bottle. The MegaBoom can also inflate 500 mL water bottles with the optional adapter (sold separately). For pellets, .22 will be most effective in creating the shockingly loud boom that characterizes this target. How loud is it? Here is a comparison from Purdue Universities noise comparison website: A military jet aircraft take-off from aircraft carrier with afterburner at 50 ft is 130 dB.