A.A.
From Insulator Wiki (Wikilator)
Type: Unknown
Manufacturer: Unknown
Production Dates: Unknown.
Country of Origin: Mexico.
Discussion: This embossing is only found on CD 154, in a variety of colors from aqua to varying shades of green. It comes in both SDP and RDP versions. Given that the Mexican market frequently copied U.S. shapes, and that the CD 154 originated in the 1920s, it seems likely that this embossing was produced sometime in the 1930s to 1950s at the very latest.