Is your power unit too loud?
Decrease that irritating sound by inserting this muffler into any central vacuum that has 2" OD diameter exhaust port(s). One muffler per exhaust port on the vacuum itself. Use a 90 Spigot Sweep Ell (part #503 in Hardware / Pipe and Fittings) to install it vertically if desired. Total Length is 13.5 inches.