You can seamlessly transfer your flight plan between ForeFlight Mobile and Garmin GTN 650/750* and GNS navigators when connected via the Garmin Flight Stream 210 or 510, Garmin’s Bluetooth wireless gateway. This makes everything from pre-flight planning to inflight re-routing easier and faster.
Here is a video that highlights this capability:
Video 1. ForeFlight and Garmin - Two-Way Flight Plan Transfer.
*GTN 650/750 only. GTN 650Xi and GTN 750Xi are not supported.