Round level vials, also known as circular level vials, are spirit levels utilized to determine the levelness of a surface, distinguished by their circular or dome-like shape and consisting of a slightly concave surface filled with liquid and a bubble. Constructed from plastic, glass, or metal, these vials are chosen for their durability, cost-effectiveness, and precision, catering to varied applications and environments across numerous industries, such as construction and carpentry, where precise horizontal alignment is vital.