Not the original but still the best
There’s no getting away from the fact that Backcountry Research invented the modern frame strap. But there’s also no getting away from the fact that I prefer the Louri Frame Strap.
It’s the better overall size and the shaped plastic eyelet/loop/thing is great at keeping the strap in check when tightening up. What is a frame strap? It’s pretty much like a roadie toe-strap on steroids. The Louri strap is more than that though. There are two anchor bungees with rubber sleeves on them that hold your stuff in place when the strap is not attached to your bike. And there’s a no-slip rubber panel on the frame-facing part of the strap to help the thing in place when riding rough terrain.
You can see from the pic what I carry in mine (mini-pump, inner tube, tyre lever and multi-tool) and although you can vary the contents a bit (go for CO2 cannister instead of the mini-pump), you can’t put much more in there. Frame straps aren’t designed for big loads. It’s about practical minimalism. If you need to carry more than this, dig out your CamelBak.