Mil-spec connectors are those that are built in accordance to a military specification.  This specification maybe country specific or universal. Generally, mil-spec connectors are designed in a way to protect the connector from environmental factors such as shock, vibration, salt spray, or extreme temperature changes. Mil-spec connectors are commonly broken out by shape or size.  Common mil-spec connector types include:   Mil-Spec PCB Connectors: Mil-DTL-55302, DIN 41612 Heavy Duty Mil-Spec: Mil-DTL-22992, Mil-DTL-28840, Mil-DTL-28876 Power Mil-Spec: Mil-DTL-12520, Mil-DTL-55181 Miniature Circular Mil-Spec: Mil-DTL-26482, Mil-C-26500, Mil-C-83723 and Mil-C-81703. Subminiature Circular Mil-Spec: Mil-DTL-38999 Standard Mil-Spec: Mil-DTL-5015, VG95234 Rectangular Mil-Spec: Mil-DTL-24308, Mil-DTL-83513, Mil-DTL-32139 RF Mil-Spec: Mil-PRF-39012, Mil-PRF-55339, Mil-C-25516 Rack & Panel Mil-Spec: Mil-DTL-28748, Mil-DTL-83527, ARINC 404/600