Team Backlog Items (TBI) are the individual elements (Backlog Items) of a Team Backlog and describe work for a single Team. The size of a TBI is initially not limited. It must be small enough in size or devided (refined) into several individual items that can be done in one Iteration, before it can be pulled into the Team Iteration Backlog during the Team Planning.
Team Backlog Items can be of different types, e.g. Team Goals as a description of a Service, a Feature of an Application or System, or a Module Version. It can also be the description of a Knowledge Gap or an Issue, or the integration and creation of a new System Version (System Increment).