A seat module electrification system includes electrical contacts on the seat and electrical contacts on the module. A gear assembly enclosed in a housing may have a drive gear attached to a drive shaft of a lawn mower and may be engaged with a driven gear attached to a driven end of a shaft. Also disclosed is an anti-allergy kit comprising means for profiling an allergic subject and an extract or series of extracts prepared according to the invention. As a result, even if a plurality of optical modulation sections are arranged in parallel, and the input ends of the signal electrodes of the optical modulation sections are arranged side by side on one side face of the substrate, synchronized modulation light of a low noise at a wide band width can be output from the optical modulation sections.