Custom Ferrules are made of alumina or zirconia ceramics, with inside diameters from 80 microns to 1100 microns, in lengths from 2. 5mm, and with features such as multi-step, countersinks, flats, slots, grooves, and chamfers. In the field of optical communication, fiber optic ferrules are a crucial component. Include single mode ferrule,multi mode ferrule,special inner. Ceramic ferrules and sleeves are often used in optical connectors, attenuators, fiber stubs, and other optoelectronics requiring low signal loss.