Sorry I should’ve mentioned. It’s for a traditional triangle frame not mtb.
Think restrap is looking most favourable for price+size/shape but I feel they're a bit cheap looking. I'm sure the quality is great like their pedal straps.
Their framebags in bigger sizes are designed to fit traditonal triangle frames.
Have you looked at the half frame bags by podsacs that are also on planetx? They are affordable and also waterproof
Have you looked at the vincita frame bags on planetx? The small one fits nicely in my medium salsa fargo, which is mtb geo as well.