The WAAS/ EGNOS enabled MR-350PS4 is a "mini" external GPS receiver which utilizes a bulkhead (7/8" through-hole) style mounting design for applications that require a more permanent weatherproof mounting solution The enclosed GPS receiver is self-contained with an active patch antenna and utilizes the latest "48" channel Sir Star IV high performance GPS chipset for accurate positioning It is also IPX7 water resistant rated