an improved retractable covering for an architectural opening includes an improved mounting bracket , an improved limit stop to prevent over - retraction and over - extension of the retractable covering , an improved battery pack mounting bracket for attaching a power supply to a head rail of the retractable covering , an improved battery pack mounting apparatus for attaching a battery pack to a head rail , an improved control system for the retractable covering , and an improved method of using a wireless remote control or a manually operated switch to activate a motor to control the configuration of the covering , including the extension or retraction of the covering , and the transmissivity of the covering . the disclosed improvements are field retrofittable .