Here we have a pencil Height marker, which can be used on circular or flat vertical surfaces.

The standard pencil diameter is approx 7mm and the way that it works is that you push the pencil into the desired height friction slot, push the pencil in as far as you want it and then mark off the chosen subject.

The height marker is designed with 5mm Increments starting at 10mm to a maximum of 115mm

Ideally the marker works best from flat surfaces.

A tricky little tool to design but will be a useful addition to the tool kit.

Thanks for Looking.