Railroads and subway systems use a tremendous amount of marking pens. Railroad workers and mechanics need to mark all of their work. The Mighty Marker® Rolling Ball Paint marker will leave a mark designed to never come off. It’s weatherproof, resistant to sunlight, marks on any surface rough, smooth, oily, rusty, wet, and stands the test of time. That is why Railroad supply distributors stock this pen and it remains a necessary tool for mechanics and other infrastructure workers.