Telescopic sights were used to increase the accuracy of aiming with various rifles and guns during both the First and Second World Wars. The user would look through the sight which would magnify their target, and would often use a superimposed image of a cross called a reticle to pinpoint their aim.
This sight would have been attached to a Lee Enfield rifle, an example of which can be seen in the Battles case in the Main Gallery. These rifles were in use by 1907 and were the rifle of choice for the commonwealth army in the First World War as it had a maximum firing range of 3000 yards.
Sights for Lee Enfield rifles were later adapted to include a wooden cheek rest for ease of use. The precision needed to fire a sniper rifle could take time to perfect, and adaptations like this would have made it easier for the user to stay stationary for longer periods of time.