I have an older 1/2 HP Screw drive unit The opener is about about 8 - 10 years old , and I am not sure of the model number. I have 4 remotes working. 3 in cars, and a keypad on the outside of the house as well as the wired switch that came with the opener. with two kids, and a wife, everybody wants a remote of their own. M question is; What is the maximum number of wireless remotes that door can handle? The remotes are a grey rectangle with 3 dark green buttons (1 larger than the other two. Any help would be appreciated.