We have been supplying these to a group in France for a while and are making more because of the demand. Here's what people are using these for: The prisms restore the geometric shape of the image after its been stretched by the projector or a video scaler or even a dvd player or Home Theater PC. Many ways to do what's reffered to as a vertical stretch. Prisms are then used to horizontally stretch the image for Costant Image Height or in some cases Vertically Compress the image for Constant Image Width. To purpose is to get rid of the black bars and increase resolution. Also it's not only a DLP projector which you can use. It is better described as a digital projector which would better refer to LCD, DLP, LCOS, SXRD, etc... There are a number of other uses for these prisms in laser applications and filmography/videography. They are made of high quality optical glass and are fully AR coated. There are two different sizes included: the large wedge prism is 110mm x 70mm (other side is 97mm x 70mm), the bottom is 38mm wide. The smaller prism is 88mm x 70mm (other side is the same - equilateral), the bottom is 30.5mm wide. New. International buyers: Our thanks to the members at AVS forums for their great descriptions!