A striker assembly for latch engagement has symmetrical sides of three intersecting plates including a mounting plate, a striker plate in which a striker throat and striker bar is formed, and a back plate which intersects the mounting plate and striker plate. The method includes identifying surface heights of plurality of tiles of a modeled wafer, and mathematically mimicking a lithographic tool to determine best planes of focus for exposure for the plurality of tiles. In some embodiments, the optical modulation is sensed by the camera of a smartphone. The kits of the subject invention at least include a primer for use in enzymatically generating an oligonucleotide tagged target nucleic acid, where the primer generally at least includes an oligo dT region and the oligonucleotide tag, and a labeled oligonucleotide complementary to the oligonucleotide tag. Detecting illumination by a second edge of the measurement image moving in a second direction, and averaging movement values related to the first and second edge illuminations of the detecting steps. The discharging circuit is configured such that it is automatically activated, when a voltage of the battery unit exceeds a predetermined threshold, to draw a constant discharging current from the battery unit until the voltage of the battery unit falls below the predetermined threshold.