I’m resurecting this thread … I’m thinking about an old strap lock system, I can’t remember the exact name. it’s some kind of black plastic disc with a rotating disc inside and when you rotate this inner disc it locks the strap, using a standard (non strap-lock) strap button.
not sure I’m clear … not sure at all 
if someone knows the name of this thing, I would be interested because I don’t want to install standard strap locks on my Grabber (because the strap button are not well located for that)
thanks !