This is a simple dry erase marker/eraser holder combo that uses 4 1/4" cylinder magnets to attach to the door in my lab. There are 4 marker holes (20mm diameter) that fit the Expo brand markers nicely. Two versions here- with or without a nameplate label ("Vascular Lab" text in photos). You can change the text in the provided sketchup file (I used 15mm tall with 1.5mm extruded height).