Was at a Firemen's Convention (Katie...even the females in the department are "firemen") in Fallon, NV this week. Stopped in at the Bird Farm Casino to get a beer, found the craps table open and bought some chips. When I got home I noticed that the $.25 had three varieties. Allan, I think your N3181 is the one on the left, note the middle one has a slanted line through the cent sign and the right one is a silver hot stamp. Of the 40 $.25 chips I picked up, 60 percent were N3181, 25 percent the middle chip and 15 percent silver hot stamp. As a random pile of chips handed over by the dealer, the percentages may indicate age and availability of the chips.