Custom printed HO scale decals representing the 10" square hazardous placards for UN 3077. UN 3077 is often found on freight cars transporting powdered materials. UN 3077 is classified as Environmentally hazardous substance, solid, n.o.s. (not including waste) [Source: Wikipedia]. I've personally noticed this placard on SP two bay gravel cars, as well as covered gondolas hauling mineral ore from the Eagle mine in the U.P. of Michigan. Being a small custom run, the size of the sheet varies but is designed to letter 6 cars, and includes the custom printed black and clear placard and an approptiate sized strip of Microscale trimfilm white.
Application requires a square 4mm x 4mm trimfilm white decal, topped with the custom printed UN 3077. Trim the custom printed sheet closely to the printing. Careful application is warranted, as you can see in the photo mine ended up a little distorted!
These are printed on extremely thin decal sheet, it is recommended to cut close to the letters. Do not scrape or rub lettering. Normal water slide decal application procedures should be followed. Visit ModelRailroadTips.com for how-to articles describing this process.