You can seamlessly transfer your flight plan between ForeFlight Mobile and Garmin GTN 650/750, GTN 650Xi/750Xi, and GNS navigators when connected via a compatible 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.