GB Flex-Hone, GB, 4-1/8", 180G The GB Series Flex-Hone tools are designed for bore diameters from 3-1/4 thru 4-5/8 and are 13 -1/2 OAL. These standard duty Flex-Hones tools are commonly used to finish and deglaze block cylinders or liners and represent a tremendous value on a cost per cylinder basis. GB41818 Yes -