The Halo is the leading economy microchip scanner. It reads the 15 digit chips and the old 10 digit chip protocols (FDX-B and FDX-A) that are used in companion animals. These chip protocols conform to the ISO Standard 11784/5. The Halo has a good read distance and is very easy to use - simply squeeze it to turn it on. It will switch itself off when not in use. It has an internal battery which is re-chargeable from a USB port via your computer or a portable device. The battery symbol on the display will show you when the power is low. Avoid running the battery to zero as this will mean you have to power it three times for 3.5 hours each session, and disconnect it between each session. This scanner has a neat feature of showing if a pet has been logged with Petlog as 'missing'. Connect the scanner to the computer USB port to get the latest listings of missing pets (from the Petlog database) loaded straight onto your scanner.