Some pretty cool technology, a device that clips onto the shaft below the grip. There is a level and/or gyroscope type device inside that makes the club 'vibrate' when you are off plane - instant feedback.
It teaches the same feels as the medicus and momentus - a pure "swinger's" motion. Startup swivel and 'fanning' are clear - to "toe up" position. I have the pro model, which has pretty tight tolerences, really keeps a "swingers" motion on track.
I'd love to see one based on a "hitter's" motion as well, could prove to be a very powerful technology for learning.
After some shipping "fun", thanks to UPS, they threw in a "grip mentor", which is a surprisingly decent aid, very much a 'hogan' grip, with clear PP#3 feel.
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"Support the On Plane Swinging Force in Balance"
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Simplicity buffs, see 5-0, 1-L, 2-0 A and B 10-2-B, 4-D, 6B-1D, 6-B-3-0-1, 6-C-1, 6-E-2