Conversion Table Metal Sign Benjamin Metals Company

Not a gas or oil sign or one with the best graphics but for $20 I couldn't pass this one up. It has good color and patina it is handy dandy for converting measurements of fractions into inches or millimeters. Without this chart one would need a 5th grader to calculate that.
Not sure if Benjamin Metals Company made the sign or if the sign was made for them. Looks like that is in Gardena inbetween the 91 and the 105. Puts it just north of the South Bay area.
The sign is 11" x 23" because someone liked prime numbers. The back is cardboard for some reason. I was going to put it outside but that would ruin the cardboard so it is my mini-mancave. Note the rest of the sign is metal but then again it could fade with exposure to sunlight. Not sure how old the sign is but is definitely vintage plus it is in the classic 213 area code.