OtterBox OTR3-1601S-20-C1OTR 1601 Series Hard Case and Magnetic Base for GPS - Black Waterproof, dustproof, crushproof and airtight protection for Bluetooth GPS Units The OtterBox 1601 GPS Case comes with a magnet base for easy mounting. Exterior Dimensions: 4.837 x 3.682 x 1.652 inches Internal Dimensions: 3.700 x 2.350 x 1.000 inches