Steel Adapter, 1-11-1/2 Female NPT To 1-5/16-12 Male JIC 37 deg Flare, Straight

That's exactly what it's designed for. It's a straight adapter going from a 1-11-1/2 female NPT to a 1-5/16-12 male JIC 37-degree flare.

Function-wise it’s a straight steel adapter that transitions from 1-11-1/2 female NPTF internal pipe threads to a 1-5/16-12 male JIC 37 degree flare, which is the common -16 JIC size.

Eaton Aeroquip rated this one for some demanding environments, including marine and military use, chemical processing, pulp and paper, food and beverage, and offshore drilling. That kind of range usually means the materials and construction are built to handle exposure, pressure variation, and tough service conditions. For a mixed operation, that breadth of listed applications is a solid sign it's not a one-trick part.