The following is a list of all the items which become available when you reach a certain level. Once you reach level 13 and can obtain the Legendary assault rifle ("Warrior Assault Rifle") you will be able to obtain all in-game items (if luck is in your favour).
Livello 2
Livello 3
Livello 4
Livello 5
Livello 6
Livello 7
Livello 8
Livello 9
Livello 10
Livello 11
Livello 12
Livello 13