On Amazon where you can now get this
Drano Dual-Force Foamer Clog Remover and Cleaner for only $4.47 or lower (regularly $7.72) after you clip the 30% off digital coupon. Prime members get free shipping.
With this foaming formula, the entire pipe is filled and thoroughly cleaned, dissolving gunk and removing odor sources. It also helps with garbage disposal clean-up and leaves it smelling fresh. It is safe for use on all pipes, garbage disposals, septic systems, kitchen drains, and laundry sinks.
