The signal is improved via a slide-out EMW (electro magnetic waveguide) element. Basically, it grabs signal that an iPhone cannot, and resonates with the iPhone's antenna to get Wi-Fi signal from every direction.
According to Absolute Technology, the creator of the Linkase, users' hands often block the phone's ability to get the Wi-Fi signal – because the EMW unit slides out, that's not a problem anymore. In fact, the creators claim that the case offers up to a 50 percent increase in Wi-Fi strength.
Absolute Technology created a chart that compares Wi-Fi signal with and without the Linkase on an iPhone 5. According to the chart, download speeds were increased, and in places where their iPhone 5 normally lost Wi-Fi, the tester was able to connect, albeit with much lower download and upload speeds than the area near the router. Of course, this test was conducted by the company making the product, so the results need to be taken with a grain of salt.
The Linkase is made with polycarbonate on the back and coated with leather to give it some extra grip. It also has raised rubber on the front to recess the screen and give it some extra protection. The rubber is also used on the sides of the case to make it easier to get on and off the iPhone 5.
The case is available in five colors — white, black, red, gray, and blue. Each case comes with an extra interchangeable EMW unit, and additional units can be purchased separately. Pricing and a final release date aren't available at this time, but the company did say it would announce more soon.