Prism-shaped device with a black plastic circular base with a wheel on one side with a wooden handle. At one end it has a small wheel with five positions depending on how sharp you wanted the pencil to be. A bit lower down on the same side, it has a small lever which moves from the front towards the back. On the opposite side there is a circular piece with three blades inside, which are operated with a small lever; when the slot opens, you put the pencil in and then turn the wheel on the other side to sharpen it. The excess pencil lead and wood shavings fell into a rectangular box which could later be removed for emptying and cleaning.
The mounted pencil-sharpener was a common feature in most schools until the portable sharpener we know today became popular. The mounted sharpener obtained a much more uniform result than its portable counterpart. However it was finally replaced by the portable sharpener, which was considered more convenient.