The Ketchum 50D Ear Tattooer is the most popular size for tattooing new born pigs (from birth to 3 days of age), dogs, cats, rabbits and other small animals. Tattoo will grow with the animal and be easy to read throughout their lifetime. Character size: 4mm (3/16"). Fast/easy tattoo character change. Comfort grip for easy long term use. Proven over decades of use. Characters specifically designed to produce an easy to read tattoo. Strong spring for quick release.