Having sold my original Wii console and its accessories, I also lost the sensor bar that was included with it. This may have been a little shortsighted on my part as I had no idea that the Wii U Basic Pack wouldn't have one, unlike the Deluxe Pack.
If like me you've then converted to the Wii U and still want the original Wii functionality, then a sensor bar is a very simple requirement. As I found out soon enough though, the loss of a wired version turned out to be a great opportunity.
This Wireless Sensor Bar has not only been designed and manufactured by Project Sustain, but it is officially licensed by Nintendo, meaning that the quality of the product meet their standards. It is superior to Nintendo's wired sensor bar in just about every aspect; even the tracking seems more accurate. It also has the added benefit of extendable sides, so if you have a group of players standing at wide angles, the bar will stick detect their remotes.
The main draw however is that it is wireless. It comes at a cost of 4 x AAA batteries, but you don't have an extra cable connected to your console and lying behind your TV. What's more, I love the fact that you can just pop it in a draw when you're not even using a Wii Remote. Operation is straightforward - one button to turn it on, and pressing it again will allow you to select between a 1 hour and 2 hour sleep mode. Press and hold to turn it off.
It's now an indispensable accessory for my Wii U and allows for greater flexibility when using the console.