Abstract: In a circular knitting machine for hosiery articles, a plurality of generally banana-shaped sinker-pressing cams are mounted beneath a lid or cap to float radially between an inner ring cam and a plurality of miniature pneumatic rams and attendant plungers, which are arranged in a circular path around the outsides of the sinker-pressing cams. Each of the rams has its plunger engaged with the outer peripheral surface of one of the sinker-pressing cams, and is connected to a pneumatic control means, which is operable selectively to force the ram plunger against the associated sinker pressing cam to urge it radially inward against the outer ends of the sinkers. With this construction the sinker-pressing cams can be selectively utilized depending upon the type of article being produced on the machine.