Office workers spend a majority of their time in front of their computer display. Therefore the display becomes a constant visual barrier and a barrier for communication. Even workers sitting across a table have to make a high effort to communicate by either standing up or walking around the table to see each other. Transparent displays have a high potential for improving this co-located face-to-face collaboration and information sharing by offering the unique ability to see screen content as well as the environment behind the display. However, with users and their screen content being always visible to others, challenges of personal and information privacy arise. Additionally, visual interference between screen content and the environment behind the display may decrease users' performance. We propose a solution by combining two transparent displays with a transparency-controlled backlight. The backlight, a piece of light guiding acrylic with edge-mounted LEDs, is opaque when turned on and transparent when off. This allows users to change the transparency of their displays on-demand and continuously, therefore controlling privacy and potential visual interference. Users can share contents instantaneously and at the same time have eye contact with their collaboration partner by interacting with the system using simple hand gestures.