How do you play a low e flat on b tuba?

There are three different ways depending on the valve type (4/3, 3/2, or 4/4).

On a 4/3 tuba, the fingering is 4-2-1

On a 3/2 tuba, the fingering is 2-1-Open

On a 4/4 tuba, the fingering is 4-2-Open