Firm grasp
A blood donor squeezes a ball during a blood drive at Joint Base Andrews, Md., May 13, 2020. Squeezing a ball causes arm muscles to contract and increase venous outflow. Units collected at the drive are transported back to the Armed Services Blood Bank Center and stored in specialized blood product refrigerators. (U.S. Air Force photo by Senior Airman Xiomara M. Martinez)

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Photo by: Senior Airman Xiomara M. Martinez  |  VIRIN: 200513-F-JT831-019.JPG