Just had a look at these. Appears to be just a battery cut off circuit. very expensive for what it is. This will not in any way prolong the life of the battery.
I have used the acu mate chargers for many years. you can leave them on all the time and they come with a quick release fused wiring attachment that yo leave on the car. They are also mean to condition the battery, however I am not so sure about this aspect. Buy comercial version, they're better and cheaper even from RS Components.
If you have access to a solar panel. A solar charger/conditioner would be the best and probably most cost effective option.
