A Ball Marker is a small disc used in the game of golf to mark the location of a ball in play, before removing the ball from the green, so the opponent can play his shot.
The Victorinox Golf Tool has an 18mm ball marker mounted on the end of the tool, which can be conveniently deployed with one hand. It is made of stainless steel and is held in position by a small knob on the reverse side.
In the older 58mm Golfer the marker was a separate item supplied with the tool.
The 65mm Executive Golf Pro has a 13mm ball marker mounted on the scales. It is made of plastic and is held in position by the small knob on the reverse side.