TrackStrap works/fits very well using the 3.0 trackers. Had to wait a long while to get them, did DIY straps while I waited for them. Happy with them.
I bought these straps with the expectation that they were the best, and they haven't disappointed! They securely hold your trackers to your body, and are nice and light and comfortable. So, when I got more trackers, getting a second set of these was first priority!
The velcro is finally starting to become harder to attach after 1k+ hours of usage, taking them on and off each time, which is seriously impressive.
(The ones missing from my picture are because I have 7 total trackers, three of which are on my Trackstrap+'s!)