Metal zipper type 5 (symmetrical)
M51 A2 NH/N_sym O-E
M51 A3 BNH/BN_sym O-E
M51 A6 G/G_sym O-E
M51 A1 G/G_sym
M51 A1 BNH/BN_sym
M51 A1 NH/N_sym
M51 A2 NH/N_sym
M51 A2 BNH/BN_sym
M51 A2 G/G_sym
M51 A3 NH/N_sym
M51 A3 BNH/BN_sym
M51 A3 G/G_sym
M51 U N/N_sym
M51 U BNH/BN_sym
M51 U G/G_sym
M51 T N/N_sym
M51 T BNH/BN_sym
M51 T G/G_sym