This is the standard female 4-pin computer fan connector. It's a 2.54mm pitch housing and features a 3-pin locking tab which is specified for backwards compatibility with 3-pin fan headers. An extra set of crimp pins is included. We recommend the inexpensive SN-28B crimping tool for these terminals. 24 AWG (0.25mm3) wire gauge is recommended but 22 AWG - 26 AWG can be used (with the correct gauge crimp die accordingly).