I recommend this to anyone who doesn't have a Zapper yet (or for those who have a Zapper and is looking to upgrade or is in need of another Wii Gun Controller (http://www.vdealbox.com/
Note: The gun features a spring kick back (which is non existent in the Zapper). This feature is important as you can fire more rapidly. Before putting your remote in make sure you take off the wrist strap as it will not fit. Not recommended for game play sessions over 1 hour as your trigger finger will get tired.
Update: Any games that are compatible with the Zapper will use the 'Z' button on the nunchuck instead of pressing 'A'. For those wondering this does not mean you can play Resident Evil 4 or Metroid Prime 3 with the Perfect Shot as it is not "Zapper Compatible" (please check the back of any game box to make sure the game is Zapper compatible or not).
This is the best Light Gun Shell I've ever used. Works great with Resident Evil: Umbrella Chronicles, Ghost Squad, and even Link's Crossbow Training.
This shell is much more comfortable than the Zapper (I own both), you can use it with one hand easily, and you have a more free range of motion since there isn't a big thing on the back of the Wii Shooting Gun to hold a nunchuck, it just can plug into the bottom of the gun (The Zapper may be better for some games, in the future, but for now I'm sticking with this).
It was built to work with the Nyko rechargeable batteries, so I don't have to take off the grip/battery cover and risk having the remote shutting down or change to regular batteries and waste those, which is needed with the zapper.
The only thing I noticed that some people may consider a problem, is that there is no way to use a wrist strap unless you physically modify the gun yourself.