Yes, it is a must. float is the tubular white object (near center of picture)...A baffle would be a shield or dam that is welded to the bottom of the tank or part of the unit itself, that basically retains fuel or keeps the fuel around the pick up screen (white object lower right corner as pictured) during acceleration,braking or turning.

Float tells your fuel gauge how much fuel is in the tank. So I guess it's not a must, if you're not worried about that, ;) .