The part pictured called the muffler is what is for sale.
The H-809VI has a small, sintered metal exhaust diffuser and is normally used with combination filter and cartridge holders (typical flow range from 1-8 CFM). The H-809VII has a large diffuser and is normally used with 4” diameter filter holders (typical flow range from 1-30 CFM).
For internal use:
Barcode 16010559 (for all quantity of 18)