Embedded contact homology of the unit cotangent bundle of the Klein bottle

We give a combinatorial description of the embedded contact homology chain complex of the unit cotangent bundle of the Klein bottle with the standard flat Riemannian metric. Using pseudoholomorphic curves coming from the associated differential, we find an obstruction theorem for symplectic embeddings of toric domains $X_{\mathrm{\Omega }}\subset {\mathbb{C}}^2$ into the unit disk cotangent bundle $D^{\ast }K$. As an application we compute the Gromov width of $D^{\ast }K$.