Alpase K100-S, 5/8″ x 9-1/2″ x 26-1/2″ ALUMINUM 6061 T6 Plate Solid Micro-Sheen Finish New. Alpase K100-S is a. The cast structure and fine-grained nature of the alloy minimize residual stresses, leading to superior flatness and resistance to distortion, even after extensive machining.