I wanna get a pair of OTB tights and they are Mondor 3350??? help please!!?

okay so i was looking on like and the website i was on was for the polertec clothing and the sizes were weird they were lke 2-4.4-6,6-8,8-10,10-12,12-14 then small mediem ,tall and x tall?? what size would i wear if i was 5'5 and 145 pounds?