Includes trap door, all gears, mainshaft, countershaft, shifter drum, detent components, bearings, snap rings, gaskets and hardware. Significantly smoother shifting than stock due to a roller detent shift drum with reduced inertia and gear dogteeth with lead-in ramping. Gear ratio of 2.94 1st gear and .86 6th gear. Fits into stock and most aftermarket 5-speed transmission cases. Bearing door is manufactured from 6061-T6 Aluminum and features wider bearings and a bearing retainer plates instead of the stock style snap rings. Gearsets are made out of 8620 steel, gears are cut before heat treating then precision ground with a diamond coated tooling for quieter operation. Lower RPM's for smoother highway speed operation and increased fuel efficiency. Redundant Neutral Smooth Shift System. Made in the U.S.A..