These dice are 10mm and have the sides: +1, +2, +3, -1, -2 & -3
You can use two of them to create a standard looking +1/+1 or -1/-1 counter or just use one as an indicator. You do you.
These were originally designed for Magic: The Gathering but many players of other popular games such as Eldritch Horror & Smash Up have contacted me telling me how useful they are in those games!
These dice are not for The Dice Pen.