At the end of each subject's storage period a ~200 mL aliquot of whole blood will be withdrawn from the unit. This aliquot will be centrifuged and the platelets extracted. The platelets will be radiolabeled with 51-Cr or 111-In. On that day, the subject will return to the Blood Center and provide a 43 mL fresh blood sample. Platelets from that sample will be harvested and labeled with the other isotope. Radiolabeling will be done by the BEST method. These aliquots will be sequentially infused into the subject. The estimated amount of the isotope is ≤15 μCi of indium and ≤20 μCi of chromium will be infused. The total radiation dose is approximately 40 μCi for a total body absorbed dose of 0.0273 rad (0.273 mSv) and a splenic absorbed dose of 3.2 rad (32 mSv). Venous samples (10 mls/draw) will be taken within 2 hours after reinfusion and on days 1, 2, 3, 5, 7 ± 1, and 10 ± 2. After these visits, the subject's participation will end and they will exit the study. Stored and fresh platelet recoveries and survivals will be determined and comparisons will be made between each subject's fresh and stored platelet recoveries.