The McAlpine 11/2" Backnut Washer Pww2 is a plumbing component that is used to create a watertight seal between the backnut and the waste pipe in a plumbing system. Here are some of its features: Size: The backnut washer has a diameter of 1.5 inches (11/2") and is designed to fit backnuts with a matching diameter. Material: The washer is made of high-quality rubber material that is durable and resistant to wear and tear. Watertight seal: The main function of the backnut washer is to create a watertight seal between the backnut and the waste pipe. This prevents water leaks and ensures that the plumbing system is working efficiently. Easy to install: The backnut washer is easy to install and can be used in both residential and commercial plumbing systems. Overall, the McAlpine 11/2" Backnut Washer Pww2 is a reliable and efficient plumbing component that is designed to create a watertight seal between the backnut and the waste pipe. It is made of high-quality rubber material and is easy to install, making it a popular choice for plumbers and DIY enthusiasts alike.