For the 5015 spec, these are as follows. Designed to carry wiring through a bulkhead or wall. Provides strain relief for the wire bundle. These are receptacles or plugs with no mounting flange. They are designed to be used on extension cables.
Strain relief is provided.
These differ from type 3100 in that they have no strain relief, and are designed to bring wiring into and out of a protected chassis. The 3102 series is the most common type of chassis receptacle used on military gear. 3106 - Straight plug. This is the most common series of plug used to mate with the 3100 - 3102 series for control or power cables. 3108 - Same as 3106, but has a backshell that allows its wiring to exit at 90 degrees.