Operability indicator device

An operability indicator device configured to be fitted to a packaging box in which a bag containing, under vacuum, a protective hood is placed, the operability indicator device comprising:

• a viewing window;
• a flag member including a first visual indicator of proper operation and a second visual indicator, the flag member configured to move between a nominal position in which the first visual indicator of proper operation is visible through the viewing window, and a warning position in which the second visual indicator is visible through the viewing window to replace the first visual indicator of proper operation, the flag member including a bearing face against which the bag is configured to bear upon an inflation of the bag inside the packaging box to move the flag member from the nominal position towards the warning position;
• a spring secured to the flag member, the spring configured to exert an elastic restoring force opposing a movement of the flag member from the nominal position towards the warning position until a force threshold is reached by the inflating bag on the bearing face of the flag member which is configured to cause the flag member to pass from the nominal position to the warning position, and
• a retainer element configured to retain the flag member in the warning position when the warning position has been reached by the flag member, so that the flag member remains in the warning position even if a force exerted on the bearing face of the flag member is reduced.