Down on the page it shows that Larsen mount having 12 feet for RG-58 cable with a UHF type connector on the end, picture doesn't show it.
Nice thing about NMO is that they are standard, and once you "buy into" that standard, you can swap antennas around really easy. Either mount will work fine, nothing magical about one brand over the other, except maybe the quality of the coaxial cable, but for a scanner, it won't matter a whole lot. Just make sure the cable is long enough to get where you need to go, nothing is more of a PITA than coming up 6 inches short. Larsen does have a good reputation, though, not sure about Browning. They've been trying to push their way into the LMR market for the last few years, even showing up at some of the trade shows. I've looked at some of their antennas, and I'm not sure if their quality is any worse or better than Larsen. Personally, I like to stick with what I know.
Also:
The Larsen NMO mount has the newer HF (high frequency) mount. They are usually good up to 6GHz, but are sort of pointless for what you will be doing. I wouldn't pay extra for it, but it won't hurt either. The HF mounts have the center pin removable, under that is a different connector that allows a more appropriate connection for higher frequency antennas. The only antennas I've seen that use them are some of the really high stuff, like 2.4GHz and above, maybe some of the newer GPS antennas. For your tri-band antenna, it isn't necessary.
