Norton CLP8501-DA-689 Architectural Door Closer, CloserPlus® arm, Multi-Size 1 thru 6, Aluminum Finish, With Field Reversible Dead Stop Arm Door Closer Multi-Size 1 thru 6. "DA" Feature Adjustable Delayed Action Closing. This feature becomes effective when the door is opened and released at any point beyond 70°. The amount of time delay Of CLP8501-DA-689 depends upon the combination of the angle of door release and valve adjustment. The valve can be adjusted with a 1/8" (3mm) hex key from no delay time up to maximum delay times of Please See Specifications, The Norton CLP8501 Delayed Action Door Closer Is Non-Handed Grade One Surface Mounted Commercial Door Closer That Is Used In High Traffic Areas In All Types Of Institutions, Hotels, Factories, Healthcare, Ect. Norton Door Controls Door Closers Are Manufactures Of Quality Made Commercial Door Hardware. See Spec Tab For Additional Product Info.