that the thin vinyl sheet of the array of microprisms can be formed as a curved dome or contoured insert to fit any desired shape of the protective overcap in fig1 the button 160 is present in the pass device as described in u s pat no 5 317 305 to operate a switch in the circuit to activate an emergency call signal it is not per sea part of the present invention also shown in phantom lines in fig1 are two plastic lenses 162 which cover two alternately flashing diodes as described in my aforementioned u s patent if desired the plastic lenses 162 of the prior known pass device can be replaced by a lens array of microprisms and a protective overcap to provide alternately flashing diodes with light multiplication in accord with this invention obviously if desired the alternately flashing diodes could be located on top of the case 138 under the disclosed overcap 148 and light multiplication lens array of microprisms within the overcap possible modified embodiments are numerous and one of those is shown in fig1 which illustrates a further small light multiplication flashing unit 170 with a molded polycarbonate case that can carry two small aaa batteries a printed circuit board and l e d 39 s 172 inserted from the top end and covered by a polycarbonate lens overcap 174 with an inserted folded sheet of an array of microprisms similar to that described for fig1 the overcap is waterproof and sealed in place on top of the unit 170 with waterproof plastic bonding so the entire unit is in a waterproof container component 176 can be a manually operated button for activating a microswitch in circuitry like that of fig1 or alternatively an.