Nintendo has created their own grip that transforms the Wiimote into a handgun, but requires two hands, much like a Tommygun or crossbow. Many people have criticized the Zapper for its awkwardness, and it was only a matter of time before a third party invented a better grip.
Nyko is no stranger as a third-party console accessory provider. They have a flavor or nearly every OEM's accessories, from battery packs to controllers, and have even debuted innovative add-on products, like their Intercooler. Nyko now introduces their PerfectShot pistol grip for the Nintendo Wii, which has several improvements over Nintendo's offering.