With knurled satin finish bodies providing positive adjustment of the hardened and radius ground plungers ensuring accurate measurement of theinternal diameter when used with a micrometer. For smaller diameter measurements use the small hole gauge. | | Set | Supplied in a size marked PVC storage wallet, with stud fastening. | Contains 1 of each size A – F inclusive. | Set range: 8 – 150mm (5/16″ – 6″).