Elongation Index (N = 6): Changes in red cell elongation index (EI) as a function of shear stress between fresh and stored cells, measured based on the length and width of the diffraction pattern, as (L1-L2)/(L1+L2), where L1 and L2 are the length and width of the diffraction pattern after: (A) 14 days, (B) 28 days, and (C) 42 Days for Fresh RBCs and RBCs stored in CPDA-1, AS-1, and SOLX. Viscosity was determined numerically by applying a second order numerical difference of the EI: (D) 14 days, (E) 28 days, and (F) 42 Days for Fresh RBCs and RBCs stored in CPDA-1, AS-1, and SOLX.