Klein bottle with coiled inlet tube, or jacketed coil with singularity and entrance at opposite ends. Theoretically gives a pair of 19-twist Mobius strips when cut.

A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle with coiled inlet tube, or jacketed coil with singularity and entrance at opposite ends, which when theoretically cut gives a pair of 19-twist Mobius strips. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three dimensions.