N female connector, 4 hole mount at 18 mm.

RF Connector Type: N. 
Impedance: 50 Ohm.
Interface Type: Female / Jack.
Orientation: Straight.
Mounting Style: 4 hole at 0.701" in 1" squared flange.
Termination Style: Solder.
Termination Type: Clamp for RG-58/U, RG-142/U.
Outer Body Plating: Silver.
Inner contact plating: Gold.
Dielectric Material: PTFE.
Note: Brass Body.