The Beattie 86170 Intenscreen for Sinar 5x7 Camera with Grid is a system which consists of an acrylic focusing screen and clear, anti-reflective cover glass.
The Beattie Intenscreen combination of a Fresnel lens and an anti-reflective glass cover plate increases the view through your 6x9cm, 4x5", 5x7", 8x10" or 11x14" camera to 4 stops.