MJ Arsenal Piston Gravity BongMJ Arsenal Piston Gravity Bong The MJ Arsenal Piston Gravity Bong elevates a smoking tradition with mechanical inspired design and high performance engineering. Featuring a first of its kind disc percolation system, this piece solves the "harsh hit" problem common in traditional gravity bongs. Handmade from premium borosilicate glass, the Piston uses a smooth gravity slide function to deliver filtered, powerful hits with every cycle. Standing nearly 9