A,
Are all your buckles stamped the same way?
I have a couple of NOS corfam straps coming, and interestingly enough there is a disparity in the stamping...will show the pics after they arrive..
I asked the master here if there was more than one supplier..he remembers it as being only one..now whether there was more than one manufacturer....
Back to your straps...interesting the thread pattern closest to the buckle...2 on the right very different to those on the left..also the keepers are slightly different sizes, not to mention the blue center sports hole..never seen this...
My guess..black is Monaco, red and brown are Silverstone...blue is Carrera....3 out of 4 perhaps...
Cheers,
D