In the 49-page lawsuit filed in California, Lululemon shows the alleged design similarities of its products with Costco’s, as well as the price differences.

Lululemon is accusing Costco of stealing from its "path-breaking" brand by selling dupes of its sweatshirts, jackets and pants.

Lululemon is suing Costco, claiming the retailer's Kirkland brand sells similar clothing, including pants and jackets, at lower prices, misleading customers. Lululemon seeks lost revenue and for Costco to stop selling the items.