Backshells for Mil-Spec Connectors

Connector Protection at its Best

A backshell is an accessory that mounts to the rear threads of a connector to enhance its operational characteristics. The primary function of a backshell is to provide strain relief, which minimizes stress from the cable, on the junction where the wires terminate to the contacts.

In addition to strain relief, a backshell may provide environmental protection by sealing the termination point between the connector and the cable from environmental factors
(e.g., moisture and dust) that can compromise the reliability of the electrical connection. A backshell can also be made to provide EMI/RFI protection when used in conjunction with shielded cable or wire braid to prevent the reception and/or emission of electromagnetic and radio frequency interference.

Backshells come in a variety of finishes, materials, and angle configurations. For material compatibility and aesthetics, backshells and connectors should have a matching material and finish. And to provide simple cable management, most backshells may be ordered in 45º and 90º angles.

Strain Relief

A strain relief backshell (i.e., cable clamp) is a supportive device that grips the cable to protect the wire–contact junction from stresses placed on the cable. Strain relief backshells do not provide any environmental or EMI/RFI protection and should only be used in clean and dry environments. Strain relief backshells angled at 90° can be used to easily redirect cables inside cramped enclosures. Strain reliefs that feature self-locking mechanisms should always be used in high-vibration environments.

EMI/RFI Environmental

The EMI/RFI environmental backshell offers the ultimate in protection. When used in conjunction with a shielded cable or wire braid, the EMI/RFI environmental backshell protects against electromagnetic interference and radio frequency interference and gives complete IP67 environmental protection. They are the ideal choice for mission-critical military and aerospace applications, or whenever sensitive electronics are being used. EMI/RFI environmental backshells are available in straight, 45°, and 90° angled configurations.


To maintain a reliable electrical connection, connectors used in harsh environments must be sealed from dirt, moisture, water, and dust. An environmental backshell protects contacts by sealing them from the elements. Milnec backshells rely upon individual wire sealing grommets or cable glands to provide complete IP67 environmental protection. Environmental backshells are available in straight, 45°, and 90° angled configurations.

Shrink Boot

38999 Series 1 Shrink Boot
Shrink boots are an alternative to metal backshells that provide strain relief and environmental sealing for applications that require low-profile backshells. When used in conjunction with specially designed boot adapters, shrink boots environmentally seal a jacketed cable to a connector. Shrink boots can also be used with a banding boot adapter to provide complete environmental and EMI/RFI protection.