The 714-100A uses our dual sensing VSR (710-125A-DS). A welcome addition to the 701 selector switch it ensures you will always have a fully charged reserve battery. When the switch is in position 1 it becomes the sensing battery for the VSR. Battery 2 which is in isolation will be charged via the VSR when the engine is running ensuring it is always fully charged. When the switch is in battery 2 position this becomes the sensing battery and battery 1 is charged via the VSR. The fact that there is always a fully charged battery in reserve is a huge safety factor. Dimensions 138L x 69W x 75H mm. 5.4L x 2.7W x 3H inches. Please note: With this system the electronic loads are run off the same battery as the engine starting, which can be a disadvantage.