• X-Small Harness fits chests 11" to 13" (neck opening is 8")
• Small Harness fits chests 12" to 17" (neck opening is 10"
• Medium Harness fits chests 16" to 22" (neck opening is 13")
• Large Harness fits chests 19" to 26" (neck opening is 15")
• X-Large Harness fits chests 24" to 32" (neck opening is 16")