What does (SG), (M), and (O) mean after a cigars name?

Those are general descriptors when a line has Maduro (M), Sun Grown (SG), and Oscuro (O) variations within a line. Sometimes a line of cigars is to small or to similar to break out as it’s own brand or line, so the cigar is designated with the above. If a line is large enough and distinct enough they may be separated, but that is not always the case.