This blood pressure sensor and cuff was part of the equipment issued to by John Glenn during his historic Friendship 7 flight on February 20, 1962.
The sensor with attached cuff is a standard, readily available piece of equipment and was one of several pieces of medical equipment issued to John Glenn to monitor the heartrate and blood pressure of the astronaut during his Mercury flight.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.