Garmin also announced the ADS-B Out and In capable GDL 88, expected to be approved for most Part 23 airplanes in the fourth quarter of this year. The GDL 88 is available with an optional built-in WAAS GPS receiver for airplanes that do not have one installed. A WAAS GPS is required for ADS-B Out to work. There is, however, an 18,000-foot limit on the ADS-B Out functionality of the GDL 88, so if you’re planning on flying in the flight levels this product may not work for you. The GDL 88 can, however, provide dual-link ADS-B In above 18,000 feet.