Constructed with 2 or 4 layers of spiral fabric reinforcement, Model 811HT also has helical reinforcing wire spiraled throughout fabric to prevent collapse under vacuum. Hose with 1/2 SAE 100R4 minimum bend radius handles vacuum applications to 28 in. Hg and temperatures from -40 to +257ºF. It includes oil-resistant synthetic rubber inner tube and oil- and weather-resistant, MSHA-accepted black synthetic rubber cover.