Those look like good antennas, but You have to pay extra for the mount with cable.
I think that a little deceptive on their part, You see $29.99, and not bad, till you read more down the page, and see that You have to have a mount, another $30.00, now the price doesn't look so good.
Why do they do this?
The mount is a standard one that will mate with hundreds of different antenna designs. You buy the mount once and swap antennas out as you desire. For example, around town, I may use a very short antenna to allow me to go in and out of a garage without issues. When on a trip, I may use a much longer gain type antenna to get good signal coverage on the highway between major cities. When I reach my destination and don't want any antenna showing, I simply remove what's there and put on a "dummy cap". Perhaps I'm going from an area that uses an 800 MHz trunking system and going to stay in an area that uses the VHF-Low freqencies for their communications. Simple, swap out that 800 MHz antenna with a VHF-Low band one and I'm set!
To accomplish this feat is quite easy, unscrew one antenna and screw the other on. This is much easier than unhooking the old antenna from the radio, pulling the old cable out of the way (cutting myself when it gets caught as it always does), removing the old antenna, coiling everything so I can put it into the trunk. Finding the other antenna, sticking it on the roof, routing that antenna's cable (those coils make it a real pain to route), notice that I left the adapter on the other antenna so go back to the trunk and fetch it, bang my head on the dash trying to reach the antenna connector on the radio, swear, hook the other antenna up to the radio, bang my head again getting out, swear again, turn on the scanner.