@CanisPundit A Copper PEX-B Barb Stub-Out 90-Degree Elbow is a fitting used in plumbing installations to create a transition from PEX tubing to copper piping. The barbed end of the elbow is inserted into PEX tubing and secured with a clamp or crimp ring, while the other end of the elbow connects to a copper pipe. This allows for a secure and leak-proof connection between the two different types of piping materials. The 90-degree angle of the elbow helps in routing the pipes around corners or obstacles while maintaining a smooth flow of water or other fluids through the plumbing system.