Chas,
This is what I had on my FX400 FT rig las Sunday at the CT State match. It's pretty durable but keep in mind it is all plastic (3D printed parts). Very adjustable as sections can be angled, added and removed to suit your likings. There are some nice metal hooks out there that are just as adjustable but I'm sure they are more $. The scorpion hook comes with a baseplate that gets screwed to your butt stock. The main part then slides up and down on this base to you preferred position and then two knobs to tighten it in place. Makes it nice to pop off and on to fit my rig into a hard case for travel.
Brian