Abstract: This lock chamber defines an elongated storage compartment with a pair of openings at the opposite ends of the same. One opening is for receiving merchandise to be stored in the compartment, while the other opening is for retrieving the merchandise from the compartment. Several partitions extend across the compartment and are longitudinally adjustable within the same. The doors and the partitions can be locked. Preferably, the compartment is formed by a semi-trailer which is located with the merchandise retrieving opening in communication with the opening of a loading deck of a grocery store or the like. The lock chamber can receive several successive loads of merchandise of different volumes and delivered by trucks at hours of the day when the personnel operating the loading dock is not available.