HP 5090-2490 is a tube reducer for joining tubing in two different sizes. It adapts a 1/4in tube connection to a 1/8in tube connection, making it useful when a tubing run needs to step down between those sizes.
This part is identified as HP 5090-2490 in product listings. Its stated purpose is straightforward: connect the larger tubing size with the smaller one through a reducer. The listings do not specify material, fitting style, or suitable equipment, so this description is limited to the confirmed size change and part identity.