Pen Holder with Neodymium Magnet Mount PKG 4 This little plastic pen holder has a spring-loaded clip to keep the pen, pencil or any other cylindrical thingy in its jaw, and a neodymium magnet in the back to stick it up on a file cabinet, fridge or other steel surface. Measures 1-5/8" x 1-1/2" in an eggish shape. Surplus alert: the magnet might stay in better if you add a droplet of glue. But you could also take advantage of its super-strongness and use it for something completely different.