(S69-8-4) COMP/MPT ELBOW 1/2X1/4

That's what this fitting does. One end accepts a 1/2 inch compression line and the other end is a 1/4 inch male pipe thread, so you get that size transition built right into the elbow. The 90-degree angle means you're also changing direction at the same connection point, which comes in real handy when you're working in a tight spot and need to route a line without a bunch of extra fittings.