VFS series is the world-first Hybrid resistance system that combines with both Fluid and Magnetic systems. The right side with many metal fins is the fluid unit, and the left side black plastic housing is the magnetic unit.

Fluid side provides smooth and exponential power gain in mid - high speed zone for simulating natural pedal feel, and magnetic side generates basic power at all speed, especially in lower speed zone which fluid cannot help. Flywheel is the machined steel type and its weight is 1.5 kgs for providing realistic pedal feel.
With this combination, VFS offers very natural pedal feel without harsh loud noise and comfortable training circumstance.
Especially for those who live in apartment house in big cities, they need to think about neighbors at all times. Nobody can disturb their peaceful life. So VFS's quiet and smooth performance is highly appreciated to enjoy daily session without worrying about neighbors.