These are very nice resin castings .  This style of number boards were used the Missouri Pacific  ubion pacific and othere roads as well for the Baldwin  As 15 thrue AS 6 1 6 models.after the rairoads retired them and others purchades then , thety ran them in this cofiguration.   You get  4 pcs   Models will have to be modified to add  them . Sive .645 w x .245 h x .190 d