Made mine from an old PC360 belt,an aluminum rod and a piece of acetal to attach to the club.
Only on protocol 3,but can already feel the effects of how it forces you to sync up your body and arms/club.
If you take the club to far inside on the takeaway (which I tend to do),the band will have some slack.
Also helps with shallowing the club on the D/S.
If you flip,you'll feel the band rub against your trail hand and loose tension.
The weirdest part is that after doing 30-40 reps with this T/A,when I pick up a club it feels like the head is attached
to a magnet for the first few swings.