Only OFW firmware that is jailbreakable is 3.55 and lower. 3.56+ cannot be jailbroke. Now there is 4.55 CFW's but they only work on a CFW ps3. Ex: My ps3 is jailbroke 3.55 but I want 4.50ITA so I upgrade. But now if a normal ps3 on say 4.40 wanted to use 4.50ITA they would have to have it downgraded assuming the model number is able to be downgraded.