These are intended to be used as distance guides. This tool/tutorial/ressource will help members, as it will avoid your wasting time on counting pixels ;) specially useful when you want to set know height/width of a glyph that is larger than the open window of the FontStructor Grid.

Copy and paste the lines that have the dimensions you need  -add more lines if your glyphs are higher/wider than the lines I show-,  to the left of the blue line and/or below the base line; put them  at 3 px distance so that they don't interfere with your work ;)

You only need to paste the lines once ;), into one of the spaces on the glyph band (putting them on a glyph slot that you don't use, it"ll be there for reference even when you switch off the green Extra Guides. Just remember to erase the lines when you've finished your font so that the lines won't disturb you when testing the font in the preview and won't stay when the finished font is being used.

This tool will avoid you having to spend time counting height and width when you want to know the dimensions of your glyph or of one you've cloned. Useful also when you have to make a font that is higher than the working space you give to your Fontstructor Grid, and when a FontStruct competition sets a certain dimension for glyphs, usually 48px (but do read the competition information!!), you'll have the dimensions ready-to-apply.