Permanently mark your animals with a tattoo outfit.  Good lasting marks can be obtained with a little care.  This tattoo outfit consists of a cast aluminum plier that holds four 5/16" characters, one set of 5/16" numbers (0 to 9), and a 2 oz. jar of black tattoo ink. 

Green ink and paste are also available.  Green is easier to read on dark eared animals.

Small - 5/16'' Digits