Sphere with three interlinked loops, the equivalent of three interconnected Klein. bottles, which cannot be cut in practice, but in theory would produce three interlinked pairs of single-twist Mobius strips.

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a sphere with three interlinked loops the equivalent of three interconnected Klein bottles. A Klein bottle has no edges, no outside or inside and cannot be properly constructed in three dimensions.