Steel drive plate set only. This ''Performance Steel'' drive plate set is identical to the Alto ''Kolene-steel'' drive plates; with the salt bath heat treated nitriding hardening process. But these Performance Steel plates are polished to achieve a lower RA controlled value surface; a smoother surface basically. This microscopically smoother surface reduces hot-spotting which helps reduce heat built-up and the occurrence of plate warpage. In short; this is an excellent clutch plate set for stock to very high performance engines and a direct replacement for the OEM clutch plate set. Incl. 5x 581912 (0.063"/1.6mm thick); 2 x 581913 (0.078"/1.98mm thick) and 1 x 581914 (0.079"/2.01mm thick) plates. Note: Compatible with OEM components and friction plates. A matching high performance Alto G3 Black friction plate kit can be ordered separately as 581910.