piston rings

looking to get new set for Nissan Micra 1.2L mk10 block . as far as I can see all rings Ebay etc show ring 1=1mm ring 2=1mm and ring( oil set) =2.8mm checking existing (worn) ring I get 1.4mm. 1.44 and 2.8mm. so stymied as to what actual ring thickness ought to be available! fitting a ring too thin will of course give major issues .too thick and it wont at least go in! any ideas out there ?