This is a spare filter retaining ring for Bestway “SAND FILTER / FILTRE A SABLE / SANDFILTER / FILTRO A SABBIA / ZANDFILTER / FILTRO DE ARENA / ПЕСОЧНЫЙ ФИЛЬТР Model / Moèle / Modell / Modello / Model / Моделъ #58497” for garden pools. I whipped this up for a friend after he had his original ring blown by freezing water inside the filter house.

This is a trivial model apart from the thread. It's almost ISO M140x4 but smaller, more like M137.5x4 - not a standard thread. I had to define it as a custom thread in Fusion 360. The result worked like a champ at first try: It fits perfectly.