The back of the sign will tell you more than what kind of grommets it has. I checked a 1939 Texaco No Smoking, and a 1946 Texaco Consignee. Both had splitback steel grommets. I checked a black Texas Company No smoking sign and it has solid steel grommets. I also checked a black Pennzoil bottle rack sign and it had split back brass grommets. I know it's as old as the heels. Go figure.