I just checked my Optima red top battery and it says on the sticker that it is MFD at Optima Batteries Inc in Aurora, CO. I have had that battery for over 13 years and still going strong, best battery I have ever had!! I bought it for $79.99 at the time, thought it was spendy at the time, probably 3 times that now. But next battery I buy for my Valiant is gonna be another!! Plus, these are gel filled so they are tough, resist heat and vibrations better, but the best is they don't leak acid.