Sewer Sentry is a sewer solution system that dramatically reduces inflow during rainstorms and lowers a sewer system’s exposure to corrosive gases, which can cause odor and become an explosive hazard. The Sewer Sentry sewer hole cover works as a manhole cover gasket and a manhole ventilation system. This manhole vent seals manhole covers with a proprietary device. The Sewer Sentry device is constructed of Dupont Zytel, a nylon resin that is impact-resistant, chemical-resistant, UV light-resistant, heat-resistant, and cold-resistant. It is also available in stainless steel.