Abstract: A protective crash helmet designed to increase the safety and comfort of a motorcycle rider is described. One of the protective layers inside the helmet includes inflatable air bubbles whose pressure and consequently size may vary when connected to an outside air pressure supply. This unique feature allows a more precise fit to a rider's head, all of which are not the same shape. In addition, the protective crash helmet also has a ventilating system for cooling the interior of the crash helmet. An air inlet located on the front of the helmet with a valving door, allows air inside the helmet whereby the passageway is the space between the respective air bubbles. The air outlet located in the rear of the helmet allows the air to pass through the helmet thereby cooling the rider.