Anyway, it turns out that the tabs on the bottom of the Elemnt that fit into the slots on the round mount "puck" are very slightly larger than on a Garmin, so the unit won't fit. To get around that, you just need to trim a tiny bit of plastic from the edges of the slot ... and only on one side. You can leave the other slot intact. The Elemnt tab will slide under the lip on the non-trimmed side, then it will slip into the trimmed slot. Rotate it 90% and you're done. The video shows my modified mount.https://www.youtube.com/watch?v=0pP-Mdkiri0
need another for the 2nd bike. Can they be used with garmin out front mounts if tweaked? Otherwise i'll head over to sigmasport and grab one.