  We present a new boundary condition for simulations of magnetic reconnection
based on the topology of a Klein bottle. When applicable, the new condition is
computationally cheaper than fully periodic boundary conditions, reconnects
more flux than systems with conducting boundaries, and does not require
assumptions about regions external to the simulation as is necessary for open
boundaries. The new condition reproduces the expected features of reconnection,
but cannot be straightforwardly applied in systems with asymmetric upstream
plasmas.
