A method and apparatus for delivering therapeutic or diagnostic agents as a low pressure high velocity spray into tissue. The EMA can also comprise a measure of the variability of its constituent values. The end portion has an adjustable second portion rotatable about the first axis of rotation, and having second engagement teeth that intermesh with the first engagement teeth to retain the second portion in an adjustable pan-position. Each upstanding support includes an arm extending perpendicularly therefrom, wherein the arms include fasteners for connection to a support surface, such as a wall.