Those are Filarmonica razors from a Spanish manufacturer that went out of biz recently. The numbers are just model number that ROUGHLY correspond to the blade size. I didn't get around to measuring my 12 spike (just honed it and shaved) but it looks to be about 5/8. Classicshaving.com carries a couple of their models, Doble Temple 10 (3/8 round) and DT 13, which is a 7/8. Even though I don't generally like to buy new/NOS razors, the Filly that I got is a highly valued member of my rotation.
P.S. Doble Temple = Double-tempered