Uni Paint PX20

Medium line paint marker, 4mm nib. 
Recommended for eggshells, Flair the nib for outdoor use. 

The Uni Paint PX20 is one of the best markers on the market. Oil-based paint in a handy marker. Marks on virtually every surface! Extensively used by manufacturers, construction professionals and hobbyists. Valve-action marker writes on virtually any surface: glass, metal, wood, rubber, stone, plastic, paper, vinyl, leather, canvas and more. The archival-quality, acid-free, oil-paint ink is fade-, water, and abrasion-resistant, ideal for projects that need to last.