Features: Built to ROAR/EFRA/IFMAR specifications CNC-machined lightweight can Aluminum end cap Lightweight design Low-resistance, silver-plated solder tabs Optimized air cooling Dual precision stainless steel ball bearings Balanced rotor High-strength magnet Adjustable timing Completely rebuildable Overview: 3-piece CNC machined can reduces weight while improving airflow, component fit, and bearing alignment. Heavy-duty silver-plated solder tabs are not only thicker to reduce resistance, but are also cupped to aid soldering. All-new stator design, pure copper magnet wire, and low-resistance collector rings. To fine-tune for specific applications and tracks, a variety of optional rotors are available. Larger precision stainless steel ball bearings have been fitted to accommodate high RPM loads. Internally, the 540-M4 is very similar to that of the 540-M3 that it replaces. The inner bearing has been moved so that it is now part of the can instead of the sensor assembly, which more precisely aligns the rotor within the magnetic field while reducing noise and vibration. Externally, the motor has been shortened, for a more centralized weight distribution within the chassis. The reduced length, combined with improvements to the can design, results in a 5-10g reduction in weight. A variety of optional rotors are available to fine-tune for specific applications and tracks.