A waste coupling is a plumbing component that is used to connect the sink or basin drain to the waste pipe. "SS" likely refers to stainless steel, which is a common material used for waste couplings due to its durability and resistance to corrosion. A waste coupling typically consists of a threaded connector that is screwed onto the sink or basin drain and a slip-joint connector that is attached to the waste pipe. The slip-joint connector allows for easy installation and adjustment of the coupling's length.
Stainless steel waste couplings are often preferred over other materials because they are less prone to corrosion and rust, which can lead to leaks and blockages in the drain system. Additionally, they are easy to clean and maintain. When installing a waste coupling, it's important to ensure that the connectors are properly aligned and tightened to prevent leaks. It's also important to choose a coupling that is the correct size and thread type for the sink or basin drain and the waste pipe.