In order for John Glenn to take photographs during his February 20, 1962 mission while still wearing his bulky spacesuit, NASA engineers modified a Leica camera with this special viewfinder. This special attachment featured a suction cup on the back side to allow Glenn to easily place the device against the visor when he was required to keep it down. The viewfinder was removeable for when Glenn did not need his visor down, and the velcro strip on the rounded top let him manage its location inside the spacecraft.
NASA transferred this rangefinder to the Museum along with all other Friendship 7 equipment in 1967.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.