Digital voice recorders; Audio recorders; Telescopes; Laser range finders; Photovoltaic cells; Noise level meters; Carbon dioxide detectors; Air quality measurement apparatus, namely, particle counters; Data cables; Microphones; LED microscopes; Solar-powered rechargeable batteries; Gas alarms; Loud speakers; Timers; Gas testing instruments; Acoustic sound alarms; Thermo-hygrometers; Radiation-measuring instruments; Sound and picture recording apparatus