L1B to L1A drop box eligibility

[Bipin77]

Hi

I recently converted my L1B(Individual) visa to L1A(Individual). Am I eligible for drop box facility? I satisfy all the conditions but I am not sure of the first condition - "I have a previous U.S. visa in the same class as the visa for which I wish to apply"

Is L1B & L1A the same class - L1?

Please suggest.