Bit Sizer is quick, simple and accurate. Accurately measures for a properly fitted bit. Molded from durable engineered resins and is fully washable. A must have for every tack box. Measures from 3" - 8 1/4". The correct bit size for your horse starts with the proper measurement of his mouth. The properly fitted bit will: Curb head tossing--Alleviate pinched-mouths--Minimize mouth sores--Reduce jaw & poll stiffness--Check excessive mouth gapping. A correctly-sized forgiving bit will increase your horses response level, build his confidence in you, and optimize his performance!