it is best when you are getting a new needle out of the package write down the size/type (i use a piece of masking tape- and place it right on the side of my machine- so if i'm going to change needles for something- i know exactly what i have in- then if it has only been
little used
i put it back into it's correct package. the packages are generally well marked- i've never tried to see the size on a needle- but i have noticed that some are (color coded) so that is another way to identify your needle.