Quarter round

A variation is a base shoe, a quarter of an ellipse.

[1] Most quarter round is of small gauge and relatively flexible.

It is typically used as a decorative build-up element in mantels and other architectural features, and at the lower edge of baseboard to hide any gaps between it and a floor.

Base shoe is used similarly in flooring applications.

Quarter round is produced in hardwood, softwood, engineered wood, and extruded plastic.