A paint spray gun has a spray cap that is disposed in front of a nozzle of a gun body, and that is formed with a central spray hole, a set of mist forming holes, a set of mist controlling holes, a pair of horn projections, and a pair of orifices. A user’s interaction with the touch screen of the device with multipoint pinch gestures facilitates navigation through large volumes of search results. The structure also includes an activation circuit operable to set the MEMS device to an error state based on a detected predetermined condition of the IC. Certain preferred chelating groups are dibasic acid residues, most preferably oxalyl, malonyl and succinyl, disulfonic acid residues, sulfoacetic acid residues and halo-substituted alkylenes.