TJC8 is a specific connector size and style. It is not specific to the number of contacts but does refer to the housing size and the spacing between contacts. TJC8 connectors are directly compatible with 0.1" (2.54mm) row pins and a slight variation of a 3 position TJC8 connector is used on hobby servos. To help protect against having servos plugged into servo extensions in the wrong orientation, many of the connector housing are molded with very slight clipped edges on one side to act as a key.