PN Racing's Replacement Heavy duty brass servo gear for the problematic 4th Mini-Z servo gear, offering confident, fast, trouble free, smooth, accurate and quite steering function from your MR03 Steering Gear box. Used by drivers and enthusiast, all over the world. Requires: removal of the servo gear box, dismantling the gearset and replacing the 4th plastic gear. difficulty level: 1thur 5? About 3.5.