Marking the middle of timber is often something that most woodworkers need to do at some point, or even offset from the centre, having such a tool handy saves time building one. Rockler's Centre/Offset Marking Tool is just that tool, taking most wooden pencils, and able to mark the centre of timber up to 38mm thick, and with the embedded magnets, it can be attached to a metal surface so is visible all of the time.
It can also mark lines that offset to the centre 1/16" to 1/2" from the edge in precise 1/16" increments (1.6mm, 3.2mm, 4.8mm, 6.4mm, 7.9mm, 9.5mm, 11.1mm, 12.7mm), using the notches on the side, so marking the edge of boards up to 12.7mm has now become something that is easy, quick and accurate.