A business card is typically .5mm and slides in easily. Use 2 or fold it in half if you want more toe-in. If you've got an extra set of hands (a helper), slide the card under the rear of the pad and have the 'helper' squeeze the brake lever lightly. The just adjust the pad accordingly. If there are no 'helpers' available, a small strap or rubber band around the lever works well . . . and no one to yell at for not doing it right.