Final answer:
A double fixture fitting is used to connect two fixtures' trap arms that are installed close together, ensuring a secure connection and compliance with building codes.
Step-by-step explanation:
A double fixture fitting is specifically made to connect two fixtures trap arms set back-to-back or side-to-side.
This specialized fitting is designed for plumbing applications to allow for the efficient and proper connection of two plumbing fixtures which are located close to one another. Using the correct plumbing fitting is critical to ensuring a secure connection that prevents leaks and complies with local building codes. The double fixture fitting is especially useful in situations where space is limited and traditional fittings would not be practical.