The Klein bottle is a fascinating topological shape first described in 1882 by German mathematician Felix Klein. It's what's called in mathematics a non-orientable, one-sided surface with no boundary. An orientable surface is one that can't be transformed into its mirror image by moving a shape along the surface. This means that the both the Möbius strip and the Klein bottle are non-orientable. To further enjoy this unique and visually delightful shape, we've made adorable tiny glass Klein bottles earrings! The Klein bottles are handmade from high borosilicate glass and hung from stainless steel ear hooks. Each earring weighs 7g and measures 7cm (about 2.75 inches) from the top of the hook to the bottom of the bottle. They function properly, with a tiny opening all the way through the neck and into the bottle.