Pin Gauge are used for the measuring and inspection of ferrule and sleeves inner diameters while Ring Gauge are used for the measuring and inspection of the ferrule and sleeve outer diameters. For standard products, please see the. The ferrule hole bore must be slightly larger in diameter than the fiber to allow the fiber to be inserted into the hole. 25 mm LC-sized ferrules are compatible with many LC/PC fiber. T&S has launched a newly engineered 800G optical transceiver featuring an MMC optical interface, designed to meet the evolving demands of high-performance data centers and next-generation network. Follow along in our step by step measuring guide as we demonstrate how to obtain the critical dimensions of a Ferrule.