This filter turns your BT-THEATRE 400TW into a compact soft panel with tunable white. Cost-effective and multifunctional: a very attractive solution for rental companies! Can also be used on the BT-THEATRE 150EZ and BT-THEATRE 250EZ How to use: Set the beam angle on the projector to maximum. Install the filter in front of the lens, instead of the filter frame. Remark: the matte side faces the lens; the shiny side faces the outside.