The products in this store are low-quality and break easily.
I'm fed up with his vulgar jokes.
high-class; high-quality; high-end; luxury · high-ranking; senior; high-level
低級 usually implies poor quality or vulgarity, whereas 下級 neutrally describes a lower rank or grade in a hierarchy.
low-level language
Compound of 低 (low) and 級 (grade, class).