“Glasslining,” a porcelain protective coating to a steel tank interior, is the plumbing industry’s most time-tested system for protection of tanks. A. O. Smith Glasslined Hydropneumatic Pump Tanks feature rolled-steel construction, and every A. O. Smith Tank is made in the U.S.A. Other A. O. Smith features include a 1-1/4" NPT spud on top for motor mount or retention tank connections, a 1/4" switch or gauge tapping on the air side of the tank, and full-size 1-1/4" connections at all needed locations.