Fiber optic pigtail has fiber connector installed at only one end, and the other end is left empty. While both ends of a fiber patch cord are terminated with fiber optic connectors. Patch cord fibers are usually jacketed, whereas fiber pigtail cables are usually unjacketed for they are usually spliced and protected in a fiber splice tray. Moreover, patch cord fiber can be cut into two pieces to make two pigtails. Some installers prefer to do this to avoid the problem of testing a pigtail cables in the field—just test the performance of a fiber patch cord, then cutting it into halves as two fiber pigtails.