Customer recently added a request to their prototype but had no idea on what hardware to use. They found this photo online, and want me to incorporate a similar adjustment feature into their product. Before I gave them an answer on the change and figure out the price adjustment, I need to find a solid source for a hardware solution

So essentially it needs to be two pieces of webbing that are joined by a pull-pin style release. Metal hardware preferred, but a proven polymer solution would be fine too.
Anyone have any thoughts? Not even sure what to search for, as "pull pin" type hardware hasn't resulted in anything worth pursuing.