You will find at the Airborne Museum online Store a large selection of souvenirs, gifts, books, apparel... about D-Day, the Battle of Normandy and the WWII. A good way to keep a souvenir of your visit... or to prepare your visit.
This brass clicker, referred to as a "cricket", is a replica of the ones used by the 101st Airborne Division during the liberation of France in June 1944. Specifically, they were used during Operation Overlord on D-Day.
Clickers were an excellent method of communicating without arousing German attention and also helping distinguish between friend and foe.