This little cactus is a nice bloomer and the orange to red flowers provide a contrast to many of the pink blooms of many cactus.
You may see this cactus also identified as Parodia haselbergii. More experts changing the names on me. The plant is native to Brazil. I protect mine in the winter and do not consider it cold-hardy.
Notocactus haselbergii is a nice specimen to use in dish gardens, as it provides a pleasing ball shape to arrange with other shapes.