# Solid Klein bottle

It is homeomorphic to the quotient space obtained by gluing the top disk of a cylinder $\scriptstyle D^2 \times I$ to the bottom disk by a reflection across a diameter of the disk.
Alternatively, one can visualize the solid Klein bottle as the trivial product $\scriptstyle M\ddot{o}\times I$, of the möbius strip and an interval $\scriptstyle I=[0,1]$. In this model one can see that the core central curve at 1/2 has a regular neighborhood which is again a trivial cartesian product: $\scriptstyle M\ddot{o}\times[\frac{1}{2}-\varepsilon,\frac{1}{2}+\varepsilon]$ and whose boundary is a Klein bottle.