The T&S Brass B-23K-NS is a Spring Check Spindle Assembly Kit designed for reliable faucet performance. This kit includes one right-hand and one left-hand Eterna cartridge, each equipped with a spring check mechanism. The spring check feature helps prevent backflow, ensuring a consistent water supply and enhancing the longevity of your faucet. Ideal for maintenance and repair, this assembly kit is compatible with various T&S Brass faucets, making it a versatile choice for plumbing professionals and DIY enthusiasts alike.