the new SK clubman chucks are made in stainless steel,as the old ones were nickel plated and they were having trouble with the plating putting the tolerances out and throwing the chucks off alinement etc;with the new stainless steel chucks they can reduce the tolerances for a more accurate chucks in centricity,the higher cost is because stainless steel costs more than the plated steel they were using before,and as stated the cheaper deal chucks are the old design,not the new stainless steel ones,cheers,
Eric.