The mount comes with everything but the antenna. There is even an 1/8" thick (if that thick) coax included that is around 10ft long. The other item you will need if the small cable that allows you to attach the antenna to your VX-170. If you take a trip to HRO or Jun's and take the radio with you they will show you what is required.

As far as antennas go Comet or Diamond are very comparable in fit, function, and reliability IMO.