U2 allows computers to automatically sense and connect peripherals, such as mice and keyboards, using different interfaces, such as PS2 and USB (universal serial bus). A bevy of Microsoft mice & keyboard products use U2; the company touts the technology as key factor in the products' success.

Unable to work out a license agreement, Microsoft considers the filing a last resort, according to Tom Burt, Microsoft deputy general counsel: "Unfortunately, Belkin has refused two years of repeated attempts to initiate meaningful licensing discussions. Several companies, including Targus, Fellowes and others, license U2 technology from Microsoft, and Belkin's attempts to use this technology for free are unfair to companies who invent, respect and pay for this property."

The asserted patents are 6,460,094 and its continuation, 6,795,949.

Belkin manufactures in China, and imports. Microsoft seeks an injunction from importation of the infringing products.

Microsoft has no other litigations of these patents at this time.