- Arm 1 will entail holding whole blood units at 20-24°C after collection for ≥ 20 hours (IP) or ≥ 6 hours (CP) prior to initiating room temperature filtration. Following room temperature centrifugation and subsequent separation, SOLX® PRBC will be placed at 1-6°C and plasma placed at ≤ -18°C within 24 hours (IP) or within 8 hour (CP) of collection. The first donation will occur with product indicated per randomization and the second donation will occur with product alternate to the randomization. Arm 1 will further entail an in vivo double-radiolabelled autologous RBC recovery substudy (n = 20-24, paired IP and CP data will be collected) and an evaluation of pre- and post-rejuvenation PRBC 2,3-DPG levels (all IP and CP units). The in vivo substudy and rejuvenation evaluation is limited to only Arm 1 and is not included in Arm 2.