let spraybottles tell you how much is inside of it

[zcamperz]

not the contents, just the amount in the bottle, like:
This is a spray bottle.
An unlabeled spray bottle. It is a small item.
It contains: (x amount of liquid)

[ZeWaka]

Makes sense that spraybottles would have a graduated scale on the side of it, for precision janitorial uses. Gotta make sure you don't expend too much of your valued cleaning juice.

(Should just be a RC_SCALE addition under rc_flags in /obj/item/spraybottle IIRC)