Mtroniks Viper Marine 20The Viper Marine20 is a brushed speed control designed specifically for use in RC model boats. It has a 20Amp 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 20Amps under load (with the prop connected, under water). The Marine20 is the perfect speed controller for anybody wanting to either upgrade their old speed controller for a no nonsense 20Amp limit reversible