One that actually required the user to peer in through a narrow blue slot, rather than seeing results on a screen.

It was a narrow slot low in the wall.

Light from the narrow slot of a window slanted across the room.

Robert indicated a narrow slot between the mountains to the south.

A narrow, white-walled slot runs through the middle of it.

There was a narrow slot with a wider hole at one end.

This is useful for working in a narrow slot where only one side should be trimmed.

Pauling was standing at the window, half turned away, looking through the narrow slot.

Then he had trouble fitting the large ballots in the narrow slots.

Down into the narrow slot of the valley thundered the black.