LIFTMASTER model 3840 residential opener is a 3/4hps screw drive. It is part of the elite series. This garage door opener has an dc motor on 110vac. A battery backup is optional. The remotes are rolling code on 315. The rail is style is Solid T.
The model 3840 is discontinued.
LIFTMASTER model 3840 residential opener owners manual and instructions in PDF format at NO CHARGE!