NRS has a few options- the usual well known ones plus a few of their own, including a mini version and titanium Pilot:
NRS Knives

I've had the Pilot (basic version) for a couple years. It's held up well so far, but then I'm not running rivers as hard as I used to. I've definitely lost a lot of knives, including from Gerber and Kershaw and Wenoka. But with the usual rubber band bit that's help keep them there until needed.
J