Wondering if anyone could tell me the estimated coverage I will get from mastic, the products most likely say on the containers but I haven't found any sites that show that information. Not sure how much I will need for seal up the ductwork in the basement that is easily accessible.

Also if anyone could recommend a site online to order some mastic. Called around and can't find any supplies places that sell it, at least ones I can walk into as a homeowner. Found a few online stores but figured I would ask for recommendations if anyone had used any before.