The radio works as expected with the magnetic base antenna. However there are no instructions for the mounting of the phantom antenna.
The 3/8 stud is too long for just a sheet metal roof. Start with a 3/8” hole. Remove the paint around the hole on the underneath side of the mount. You will need to add a stainless steel washer and/or a star washer under the sheet metal. At least the star washer to ensure a good ground. Discard the nylon stepped washer (used for brackets with 5/8 hole). From the topside, screw the base onto the stud. The antenna should now screw on and seal off against the sheet metal roof.

I bought this for my UTV to upgrade power from an older MTX 105 5 watt to the 15 watt. Everything is excellent quality. Everything is included. Excellent antenna and coax and mounts. We talk 8 miles in hills and canyons and miles to the handhelds (which other UTVs in our group have.) We put an MTX micro mobile radio in the front of the UTV pack and 1 in the rear because we can reliably talk for miles. I installed the 5 watt in my truck. That works great travelling with campers and motorhome caravans. Be sure to install coax with NO tight coiling of coax! Do research on proper installation, and you will be super happy with RX and TX results!

I purchased 4 of these bundles to try out on our 3200 acre farm. Got one for the combine, two in tractors, and one in the semi. They are super compact and simple to install. There's no programming or anything required. We just turn to channel 18 and start talking! We're about 11 miles from the grain elevator and are able to communicate from the farm to there. We mostly use the radios for combine to grain cart communication. I plan on buying 4 more in the near future to fully outfit our operation.