RTS88 Series, Dorma Overhead Concealed Door Closer, This Closer is Designed to Give Lasting, Dependable Service Where Surface Applied Units and Other Types of Closer are not Suitable, or Would Interfere with the Architectural Design, This Closer can be Easily Installed in Wood, Aluminum, Hollow Metal Doors and Frames, For Single and Double Acting Doors, Dependable and Easy to Install, Hold Open, 90 Degree, Size 3, Aluminum