How is licensing SMBR for Microsoft Exchange Server in two controller array with Premium Bundle

Hello,

Could you say, how is licensing SMBR for Microsoft Exchange Server in two controller array with Premium Bundle?

Look at the screen:

We have here SMBR (2500 mailboxes) and two controllers, does it mean that I can use 2 * 2500 = 5000 mailboxes on the array?

Or it's 2500 mailboxes  for the whole two controller array?

Thanks in advance