Pressure gauge for an inflatable article

An inflatable helmet comprising:

• a pressure gauge, the pressure gauge comprising:
• a housing;
• an indicating chamber defined within the housing;
• a resilient diaphragm located within the housing and configured to expand upon an increase in pressure within the inflatable helmet, the diaphragm having a first surface and a second surface opposing the first surface, wherein the first surface of the diaphragm is configured to be in fluid communication with an interior of the inflatable helmet and wherein the second surface of the diaphragm defines a boundary of the indicating chamber;
• and
• an indicating element located within the indicating chamber, wherein the pressure gauge is configured so that the indicating element is moveable, by an expansion of the diaphragm, in a first direction away from a first position and the position of the indicating element relative to the housing provides an indication of the pressure within the inflatable helmet,
• wherein the inflatable helmet has a helmet shape in an inflated configuration.