It is most common in single cat households where the cat is alone of much of the day. (felinedocs.com)
Designed for single cat households or cats under 15 lbs. (amazon.com)
Even an indoor cat needs to have annual exams to look for age related changes and may require vaccines for upper respiratory tract infections that are very common in even single cat households. (halifaxveterinaryhospitalinc.com)