Please help: what is visa# ?

hi,

I am prepare the documents for I-485, could you please tell me which# is visa number? Is it I-94 number? I checked all numbers on my F1 visa (I use F1 visa when entered US, but now I am holding a H1B). I only found a small red number near the right-bottom corner. Is it visa number? Seems the I-94 number is refered in more places. I am confused which is so-called visa number. Thanks for your help!