Hager 5100 Series Grade 1 door closer is constructed of cast iron, which makes it ideal for heavy duty, high use and abusive environments. Hager door closers are the only closers in the industry that are both BHMA certified and backed by a lifetime warranty. Heavy duty, Grade 1 door closers are ideal for schools, hospitals, and other high-use environments. The delayed action feature is available for all 5100 Series applications. The closing time between 90° and 70° shall be a minimum of 20 seconds, but is adjustable to be even slower. The 5100 Series closer offers an adjustable spring feature for sizing. Spring power of the closer can be increased or decreased by turning the power adjustment shaft clockwise.