M-Theory on Orientifolds of $K_3 \times S^1$
  We present several Orientifolds of M-Theory on $K_3\times S^1$ by additional projections with respect to the finite abelian automorphism groups of $K_3$. The resulting models correspond to anomaly free theories in six dimensions. We construct explicit examples which can be interpreted as models with eight, four, two and one vector multiplets and $N=1$ supersymmetry in six dimensions. 
Alok Kumar and Koushik Ray