This is a metric scribing tool. You can place a pencil through the hole and then scribe your material for a perfect fit. Great for carpentry, cabinet installing, construction, and general woodworking.

How to use:

Insert your sharpened pencil through the hole. The engraved numbers show the distance from that edge to the point of the pencil respectively. Place your chosen flat edge on the reference material (i.e. an uneven or wavy wall) and draw on the piece of wood that needs to be cut to fit. Then can cut that piece of wood along that line for the perfect fit.

I measured a bunch of different pencils I had laying around and chose a hole size that worked the best. It's a nice snug fit for my pencils, but since not all pencils are the same, you may need to try different ones or reem out the hole if necessary.