The housing is 3D printed from tough ABS. It sits securely atop a standard RBC2 battery, and connects to the tabs on the battery. It provides safe, secure power distribution and charging. With an integrated 50 watt automatic solar controller, the BatPac Solar is an amazing device that is completely unique in the portable power industry. It will handle up to 5 amps of DC charging current, and uses a PWM algorithm for a smooth, accurate tapered charge. The volt meter is low-draw, with a responsive, accurate LED display. When a solar panel is plugged in, the voltmeter will display the incoming voltage of the panel. This allows you to confirm that the system is receiving power via solar. If the solar panel is unplugged, the meter automatically changes to show the voltage of the battery it is attached to. The Solar panel is plugged into the BatPac via a pair of power poles above the volt meter. These power poles are in a non-standard (sideways) configuration. This is to ensure that the user does not try to power a device through the solar connection, which would not hurt anything, but would not work, of course. If you intend to use one of the common DC barrel connections (5.5 x 2.1) like our 28 watt panel, you can purchase an inexpensive adapter to make the connection plug-and-play. This BatPac will ONLY fit onto a RBC2 battery. The BatPac Solar is 5.9″ x 2.5″ x 0.5″ and weighs just 4.0 ounces!