An electroluminescent phosphor comprising ZnS-based phosphor core particles and a coating layer provided on the individual core particles, the core particles having a mean particle size of 0. An elongated, unitary molded member terminating in a bulbous first stop member having a diameter greater than the diameter \u201cd,\u201d an axle portion of diameter less than \u201cd\u201d proximate said bulbous portion, and a second stop member spaced from said first stop member adjacent said axle. If there are fluctuations in dimensions or a change in temperature, because the vibration mirror is one, all the colors are subjected to the same influences. More preferred bubble caps have a relatively high skirt height or long slit length, or both. The detents and tabs engage with one another to removably couple the cushion device to the frame member. A shock penetration transducer communicates the movement of the coupled rods and sampler to output a third electrical signal that is a function of the sampler penetration due to the hammer blows.