Caliper Accessory Centerline Gage For use with 8" & 12" Calipers with 0.180" Thick Jaws Pair of conical probes specially designed for calipers to quickly measure centerline distances. The 60° conical probe snugly fits into holes and takes away guesswork from center distance measurements. Features include... Diameter "A": 0.500" Overall Length "B": 2.750" Slotted Width "C": 0.183"