But just as the choice of mates in a purebred line can have splendid, or disastrous, results, randomly choosing two breeds to mate could also create unforeseen consequences. (articles.orlandosentinel.com)
It also reduces a male dog's inclination to roam in search of a mating partner, which can reduce the chance that your furry friend will ever get lost. (fetchpetcare.com)
UPDATE: It appears that rather than two versions of the Mate S, there's actually three. (pocket-lint.com)