Amazon.com Inc. said Oct. 23 that it will add the stores of GNC Holdings Inc., Health Mart Systems, Inc. and Stage Stores Inc. to its Amazon Counter network.

Counter, which was launched in the U.S. in June, allows customers to pick up online orders from Amazon Lockers installed at the locations of partner retailers.

Amazon said it has been trialing the service with health and wellness products maker GNC, community pharmacy operator Health Mart and specialty department store chain Stage Stores for the last few months.