MTX Performance Brake Disc Rear Solid Round Harley Davidson MD524 #11018MDS11018 MTX Performance Brake Disc (Rear Solid Disc) [HARLEY DAVIDSON XL883 N 2011 2015] Drawing from its immense racing experience, MTX has refined the performance and tolerances now offering applications for almost every motorcycle brand and model on the market. Performance at your fingertips. Discs sold singularly. Solid discs Constructed using one complete segment of Japanese SUS 420 stainless steel, then heat treated to HRC 36+ 2 standards.