This firm produced perfins in 1910.
Here is a Rodríguez González é Hijos cover produced in that time:
Used 1910(?) from Saltillo to Rochester, New York.
"6 point star" perfin on 5 centavos Miguel Hildalgo stamp (1910) - Scott 314
Here is the only known stamp which has 6 Point Star (La Estrella) perfin:
Advertisement Translation: "We can guarantee to the public, that given the improvements of our machinery and the good
class of wheats available to us, that the products of our MILL will always exceed in class the others of the same system.
In addition to the superior quality of the products, the consumer will find EXCEPTIONALLY INEXPENSIVE products in this house.
Saltillo, Coahuila"