GP2513 SystemPod Pre-Cut for Raymarine a75/a77/a78 & 1 Instrument for 12" Wide Guard, GP2500 Series for 12" Guard, SystemPods for Sail are for mounting multiple pieces of electronics in one NavPod. This is a good way to reduce the height of a system. In addition to mounting a radar or chartplotter, you can have room for an autopilot, instrument, stereo controller, or VHF mic. A SystemPod is best mounted on a Single Bend AngleGuards. SystemPods for Power are for mounting on a SK135 Stachion Kit can be used to mount a SystemPod on a flat surface, such as the flybridge. Stachion Kits can also be used with a SystemPod for overhead mounting applications. Usable Face: 15.05"W x 6.25"H, Instrument Cutout: 3.6". Acrylic capped ABS plastic, Chromed stainless steel tamper-poof fasteners, Double seal for watertight integrity, Models are available pre-cut for popular electronics, Stainless steel mounting hardware and mounting gaskets.