Here's how B&H describes this Linhof jewel:
"A truly versatile accessory which not only determines with accuracy the selected picture area, but can also be used to determine the focal length if the location is already known. The photographer can use the viewfinder by itself to establish the focal length and selected picture area by turning the focal length ring. The Multifocus Optical Viewfinder is also used to determine the correct place for the camera. If focal length and image field have already been determined, it is easy to find the correct place for the camera with the aid of the viewfinder, which means that it is not necessary to keep moving the camera and tripod. B&H price: $2088.50"
Unused, like new, $1175 + shipping
Reinhold
www.re-inventedPhotoEquip.com
"A truly versatile accessory which not only determines with accuracy the selected picture area, but can also be used to determine the focal length if the location is already known. The photographer can use the viewfinder by itself to establish the focal length and selected picture area by turning the focal length ring. The Multifocus Optical Viewfinder is also used to determine the correct place for the camera. If focal length and image field have already been determined, it is easy to find the correct place for the camera with the aid of the viewfinder, which means that it is not necessary to keep moving the camera and tripod. B&H price: $2088.50"
Unused, like new, $1175 + shipping
Reinhold
www.re-inventedPhotoEquip.com