Complex sentence: The most common theory of fitting the snaffle is placing it in the mouth so that it creates two wrinks on the lips of the horse, and if the horse has long lips, fewer wrinkles may be present.
Split into simpler sentences: The most common theory of fitting the snaffle is placing it in the mouth so that it creates two wrinks on the lips of the horse. However, if the horse has long lips fewer wrinkles may be present.