Swift offered a few roof prism designs in their highly-touted Audubon binocular line, like the model 825, 827 and model 828.
The Audubon 8.5x44 model 828 has BaK-4 glass prisms and fully multi-coated optics for optimum light transmission and sharp, clear views. Lightweight for a 44-mm objective lens binocular, the 8.5x44 Audubons weigh just 23.4 oz. With a minimum close focus of 9 feet and a 336-foot field of view at 1000 yards, you won’t miss anything with the 8.5x44 Swift Audubon binocular. Adjustable twist-up eyecups and 19 mm of eye relief make the Swift Audubon 8.5x44 binoculars comfortable and easy to use. Swift Audubon binoculars are waterproof, shockproof and internally fog-proof. Swift Audubon binoculars are supplied with a neoprene neck strap, ocular and objective lens covers, a microfiber lens cloth and a padded field case. The 8.5x44 Audubon binoculars are backed by the Swift Premier 25-year warranty.