These tubes are used to replace a TRM-CC core that has been damaged or heavily contaminated. The replacement cores come in three sizes: 9", 35" or 59". To replace a damage core, the outer perforated protective screen is unscrewed and set aside. The old connecting wires are cut leaving as much wire as possible attached to the head assembly. The old core is unscrewed and the new core is screwed into place. The new core is connected using the enclosed IDC splice and the outer screen is carefully replaced.