This low cost, unmodulated, 0.8 milliWatt helium-neon laser is perfect for student's hands-on demonstrations. Use it for making holograms, measuring precise intensity of the laser output, or examining the finer details in a diffraction pattern. Use in a darkened room. Features: • Hard seal laser tubes provide long, dependable life • Impact-resistant, see-through, two-tone acrylic case • Tamper-resistant screws for safety 120 VAC 60 Hz. Dimensions: 36.7 x 7 x 5.8 cm.