I haven't been able to figure out which the 245 uses, but I've been wondering if it's 5.0. Syncs seem faster to me and anecdotally the music version has better connection to headphones than older Garmin watches (which assumes the headphones are 5.0 as well). Also Garmin is pushing into IoT with ConnectIQ 3.1 and I think many of those devices use 5.0.
