MFJ-310S

The MFJ-310S is an auto window mount for mounting a SMA type handheld antenna on a car window. Strong metal construction with rubber guarding protects windows and secures it when you roll your car window up. It features a 10 foot (2.5 m) RG-174 coaxial cable terminating in a SMA male plug. You will notice a significant improvement in performance by getting your HT antenna outside the car. 
Please note that the antenna shown is not included.

(If your antenna is BNC and not SMA, please see the MFJ-310.)