20" Zambuto F/4.0 Primary

I have a 20" f/4 mirror for sale. The focal length is 80.8", and it weighs 46 lbs. It was produced by Carl Zambuto, so excellent quality is assured. I've been using it for photometry work housed in an observatory for 5 years. The coating is no longer pristine, but it is perfectly servicable and has several years of use left. The original cost for this was $7300. If interested, I can supply the documentation from Zambuto Optics. Thanks for looking!