Polycom, Inc. PY-2200-48890-025 VVX EM50 Expansion Module for VVX 450.Ease of use-Large, high resolution 5.0" screen with programmable line keys that provide an simple, intuitive user interface.Ease of installation-Setup is fast and easy, as signaling and powering are provided by the VVX 450 host phone.Increase productivity-Provides advanced call handling capabilities with a visual experience that simplifies contact management.Leverage previous IT infrastructure investment- Maximize your Polycom VVX 450 business IP phones by equipping them with EM50, turning them into fully-enhanced personal desktop solutions