Lululemon is reportedly suing Calvin Klein, claiming the U.S. brand infringed on three of their patents -- specifically the ones they use to make their high-performance (and ridiculously popular) yoga pants. In turn, the company is seeking unspecified damages, including money to make up for lost profits.

The success of Lululemon is almost exclusively based on the popularity of their comfy yet fitted pants.

And though the brand's popularity is still evident -- in the number of people who wear their gear -- sales have dipped in the past few months, leading analysts to wonder if their rapid expansion and growth will diminish.

Part of the issue of this lawsuit, says The Vancouver Sun, is Lululemon is rapidly expanding in the U.S., targeting the same "market" many other designers are going after: the young, professional woman who wears upscale athletic gear to workout.

Check out some of the current looks -- not just pants! -- that are currently available at Lululemon.

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