My company uses a barcoded Asset tag to track hardware. I recommend tagging to my customers – it should be a unique randomly generated string, barcode scannable (or QR Code), placed n an easy to access spot on each hardware device. Asset tags should not be informational – else folks will want to cahnge them if the device is repurposed. For devices hard to reach, hard to scan, rfid tags are preferred, even the most inexpensive that can be wanded with the right inexpensive technology.