Enhanced variable-height mounting arms comprise structures that allow any of improved cleanability and/or improved adjustment of height or counterbalancing. An exemplary enhanced variable-height arm comprises an upper shell structure that substantially extends over the upper and side regions of the mounting arm, forming a four-bar linkage. A lower cover is mounted to the upper cover across the bottom side of the arm, and defines holes therethrough for extension of the opposing ends of the arm. The variable-height arm further comprises a bias element, wherein one end of the bias element is adjustably fixable in relation to a defined curve, non-linear path or slot, such as within a curved slot. The variable-height arm may preferably further comprise a mechanism for adjusting any of the height or counterbalance for the structure.