Example implementations relate to a fan module. The fan module may include an outer impeller having a first plurality of radial blades arranged between an inner circumference of the outer impeller and an outer circumference of the outer impeller. The outer impeller may be rotatable about a first axis of rotation. The fan module may include an inner impeller having a second plurality of radial blades, the inner impeller disposed within the inner circumference of the outer impeller and rotatable about a second axis of rotation.