For a towel radiator, rotate into place. There is an optional clip which I don't find necessary but would help if the hook falls out. Two sizes, 1 is slightly larger. Avoid using too much force to fit these, the joints could be broken by the leverage.

Works fine in PETG, might be a bit soft in PLA. First version lasted 3 years with a large bath towel and was not printed particularly well.

Check your min layer time and fan settings if the top melts. Should print OK without supports.