they are rare, very short production run, I have an advertising leaflet somewhere....
I remember SFS did a supersport in a CS700 stock (or whatever their thumbole was then) with a gas ram fitted for a short while - a really handy little rifle but they had a real problem with power going up, as did the gas rammed thumbhole superstar...
"But we have our own dream and our own task. We are with Europe, but not of it. We are linked, but not comprised. We are interested and associated, but not absorbed."
Winston Churchill 1930