Powerlatch Pneumatic Door Closer.  Includes storm safety chain with shock absorbing spring and hold-open slide slip for multi-position hold-open feature.  Adjustable speed control with check valve for positive latch force.
 
Fits most steel security storm doors, screen doors, or other doors with a 2" mounting rail.  Can also be attached to center panels if the door has an existing closer bar positioned between the glass panels.