Small
Girth around the rib cage (red color on the picture): 20.5-28.5 inch (52-72 cm)
Around the neck (green color on the picture): 17.5-25.5 inch (44-64 cm)
Chest strap (blue color on the picture):23 inch (57 cm)
Medium
Girth around the rib cage (red color on the picture): 26-34 inch (66-86 cm)
Around the neck (green color on the picture): 20-27 inch (51-67 cm)
Chest strap (blue color on the picture): 23 inch (58 cm)
Large
Girth around the rib cage (red color on the picture): 28-37 inch (71-94 cm)
Around the neck (green color on the picture): 28-35 inch (71-89 cm)
Chest strap (blue color on the picture): 25 inch (64 cm)
Extra Large
Girth around the rib cage (red color on the picture): 35-47 inch (89-119 cm)
Around the neck (green color on the picture): 28-35 inch (68-90 cm)
Chest strap (blue color on the picture): 28 inch (70 cm)