The “No‑Kink Hose Bib, ½″ FIP, Lead‑Free Brass” you mentioned corresponds to the Arrowhead NK50F (standard model), while the NK50F‑QT is the quarter‑turn version. The difference is in the handle mechanism — NK50F uses a traditional multi‑turn wheel handle, NK50F‑QT uses a quick quarter‑turn lever.