A dispensing gun has a gun body, a first component inlet, a second component inlet, a dispense head, a first valve, a second valve, a clamp, and a trigger. The gas-phase product flow can be substantially continuous, low-temperature, unsaturated with respect to the vaporized vaporizable liquid, and of substantially constant vaporized vaporizable liquid concentration as a function of time. Standard PCB board-to-board connectors may be provided at an edge of the circuit board and a further circuit board provided with a series of conductive tracks may provide both a mechanical and electrical connection between the circuit board and the light sources. Length of the leg can be adjusted to best size as per different head shape.