It will work fine on 2m and 70cm...
I've used this antenna, same stock number, before... In the actual product instructions that come with the unit it states you may use it on 144-148 MHz and 440MHz UP TO 25 watts.
Unfortunately, it would appear one cannot download the actual owner's manual from Radio Shack product support at this time.
I have used it on these two bands without incident, following the recommended power maximums.
The magnet is not-so-strong, however, so make sure you affix it to a good piece of steel and keep it under 80 mph.
And for those who just bad mouth radio shack for bad-mouthin's sake, please examine the country of origin of most of your beloved ham radio products... Japan, Korea, Taiwan, China. Same place this antenna is made, amigos.