Ideal gift for a math or physics student, scientist, or computer programmer. Does not work as mousetrap. From Cliff Stoll, the Klein bottle guy - made from quality, low expansion borosilicate glass - microwave safe. Clear, non-colored, transparent glass. Zero volume, one-sided, nonorientable, 3-dimensional, unbounded, locally Euclidean About 8" tall, 4" diameter (20x10cm), weighs about 8oz (230g), ∇·B=0 and ∇×E=−dB/dt Rustproof, Batteries not needed, Riemannian, baryonic, satisfies Gauss-Bonnet theorem, free of any magnetic monopoles.