This is going to take your 20v or 18v batteries and regulate them down to a 12.25vdc output. This is for all of you that need to run products that can not be ran on 20vdc. Do you research and see what your unit can handle voltage wise. We know the Garmin units are good and do not need this product but the hummingbird, lowrances, etc are not able to be ran at these high of voltages and therefor need this voltage reducer. This reducer is rated from 8-40vdc and will output 12.25vdc up to 6amps.