I would suggest lower casing the "M" as it stands for "meters" . By reading the submission title (the article one is correct, I don't know why you changed it) I couldn't figure out which mega units it was referencing (pixels, bytes,?)
I saw this comment several hours after submission and it was already too late to edit the title. I copy/pasted the title from the blog, so I guess it’s HN who capitalized that letter.