Diode laser emits 635-nm light and is ideal for conducting laser and optical experiments including voice and audio optical transmissions. Features include externally adjustable internal electronic amplifier suitable for low-voltage microphone inputs and higher amplitude AM/FM radio signals, analog (1 to 500 kHz) and digital (1 to 500 kHz) modulation capabilities, fool-proof beam stop, impact-resistant case, tamper-resistant screws, tripod mount, skid-proof rubber feet, full-color operator's manual, and 4-year manufacturer's warranty. Case dimensions are 5.6 x 7.5 x 22 cm.