18" Big Octopus Perc Bong With Matrix Diffuser18" Big Octopus Perc Bong With Matrix Diffuser. Engineered for CLEAN AF hits, the Big Octopus Perc Bong With Matrix Diffuser is a beast of a bong that doesnt hold back. Standing tall at 18 inches, this double chamber setup a premium filtration fortressstacked with an octopus percolator and matrix diffuser that cool, clean, and soften every hit. Made from thick, heavy duty glass and fitted with a 19mm female joint, this stemless glass perc bong