Small-Medium: 10-17" (25-43cm) long x 1" wide
Large-XXL: 18-28" (46-71cm) long x 1.5" wide

Colour-coded to indicate your dog's temperament and needs:

Red - CAUTION (dog needs more space)
Orange - NO DOGS (doesn't enjoy the company of other dogs)
White - DEAF/BLIND (dog can't hear or see you)
Yellow - NERVOUS (nervous dog, needs more space)
Blue - TRAINING (don't pet or approach without owner's consent)