Meldes Vibrating String Apparatus, consists of a string and an oscillator to generate different frequencies, Requires 6 V, 50 Hz power source, with 4mm plug leads, Weight (lb): 1.4, Length (in):11.0, Width (in):6.0, Height (in):3.0
Optics Kit - Junior, 2.6lbs, 15.0x11.4x4.3inch, ray box with bulb and flex having two 4 mm plugs, a pair of blanking plates, two slit plates, Planoconvex lens, color mixing set, frosted concave lens, frosted convex lens, frosted semicircular lens