The Viper Marine40 Plug 'n' Play is a brushed speed control designed specifically for use in RC model boats. It has a 40Amp motor limit, what this means is that you can use any, DC brushed motor, as long as the current drawn by that motor does not exceed 40Amps under load (with the prop connected, under water). The Marine40 Plug 'n' Play is the perfect speed controller for anybody wanting to either upgrade their old speed controller for a no nonsense 40Amp limit reversible electronic speed control or for anybody who uses scale model RC boats at scale speeds and doesn't want the added job of setting anything up! The Plug 'n' Play is a popular choice from the ever popular line of Viper marine speed controls, this is due to all the features that are included, such as a built in failsafe, 100% proportional, fine throttle control in both directions, and motor stall protection, which is a feature that cannot be overlooked when a possible encounter with weeds is always just round the corner and also the automatic calibration to your radio system as you use it. Not to forget that the Viper Marine range of speed controllers are all completely 100% waterproof and designed to work on fully charged 12V Lead Acid batteries!