These silencers can come in various shapes such as, rectangular, oval, and round. The shape selected is determined by the space available. They are commonly used in generators located in sound attenuated enclosures. The silencers must meet National Fire Protection Association (NFPA) guidelines.

Combustion gases are comprised of many of gases. Some of the gases are extremely harmful and some are not so harmful. The Environmental Protection Agency (EPA) enforces exhaust regulations to reduce harmful exhaust gas emissions. 

The EPA closely regulates emissions for generators that supply main power to a facility. Current Tier IV regulations require the use of a catalytic converter. The basic converter is constructed of a honeycomb grid design that is placed in the exhaust system directly after the exhaust manifold. This location allows the exhaust gas to be at the maximum temperature needed for proper operation. Many new silencers combine the converter design with the silencer.