Like the astrological sign, the Gemini vest is a two-in-one that can be worn reversibly. On one side is the red corduroy fabric, and the other is tan faux suede. For the indecisive minds, Velcro straps will allow for easy change. PuppyPAWer from Dogo. Measuring Guide: Back: Measure length of pet's back from the base of the neck to the base of the tail. Neck: Measure the circumference of the pet's neck for a snug, not tight fit. Chest Girth: Measure the broadest part of the chest. Note: If the dog has a stout build, select one size larger.