The ET-C1S600 1.36-2.10:1 Projector Zoom Lens by Panasonic is an optional accessory compatible with PT-REQ and PT-REZ series projectors. Designed as a standard-throw lens, it is ideal for distances ranging from one and a half to two times the image width. For instance, this zoom lens can effectively project onto a 15-foot wide screen with a 16:10 or 16:9 aspect ratio from distances between approximately 20.5 feet to 31.5 feet. When used with a 4:3 aspect ratio image, the lens provides a throw ratio of 1.64-2.52:1.