Reebok International Ltd. has filed a lawsuit against Nike, Inc. in the U.S. District Court for the Eastern District of Texas, claiming Nike infringed on a patent arising from Reebok’s collapsible shoe technology.

The complaint identifies several Nike men’s and women’s shoes that Reebok clamins infringe upon its patented flexible sole technology, which also allows shoes to be collapsed for travel or for packaging. Infringing products include 11 different Nike shoes marketed under the “Free,” “Free Flex,” “Free Zen & Now,” “Free Trainer,” and “Free Trail” product names.

The Reebok patent protects technological design features of a system that includes flexible materials in the product’s sole. The suit alleges that despite Reebok’s patent protection, Nike “willfully and intentionally” developed shoes that use Reebok’s technology.

“Reebok is a recognized innovator with a commitment to continuous improvement of footwear technology for the benefit of our consumers. We will act to protect our research and development efforts whenever companies try to claim Reebok technology as their own,” said Diana Wainrib, Chief Counsel for Reebok.

In January of this year, the U.S. patent was issued for Reebok’s flexible sole shoe technology.