An adjustable storage system is provided which includes a flat base, an upstanding fixed side attached to the base, and an adjustable slideable side which slides laterally on the base and cooperates with the fixed side to provide lateral support and containment for packages placed therebetween. A guiding mechanism allows the sliding side to move freely. The system further includes a locking mechanism to secure the slideable side in a given location. The slideable side also includes a hand grip and thumb control button operably connected to the locking mechanism to lock and unlock the slideable side. The preferred embodiment also includes a telescoping member which extends between the fixed and slideable sides to support the sides and to prevent packages from tipping.