This cello-shaped cello mute works on the same principle as the round mute, except that it only goes over one string, not two.
The mute stays on the instrument when not in use and is then easily slipped on to the bridge when required. When engaged, the mute sits across either the G or D string, muting the bridge. Made of rubber the mute will not damage your cello strings in any way.
There is a small nib on the top which makes it easy to grasp.
Some players prefer the Tourte cello-shape mute to the round one as it is more secure when not in use.