A robot gripper for moving wafer carriers and packing materials and a method of operating the same are provided. The gripper mechanism has two clamp assemblies, each with a support pin at the bottom. The clamps are configured to move towards or away from each other, and the support pins are configured to move relative to the clamp assemblies. The first clamp assembly has a main clamp and a secondary clamp with a protrusion, while the second clamp assembly has a similar configuration.