A Size 

• Sides from bottom of ring over to bottom of ring on other side 23-29.

• Browband- In front of headstall straps 10.5

• Top nose band strap is 7.5

B Size

• Sides from bottome of ring over to bottom of ring on other side 26-33

• Browband- in front of headstall straps 12

• Top nose band strap is 9