The Hammerlin CD-57 Pulse Gun is a Human weapon developed on Earth following the Taelon's arrival on the planet. It was developed with the capacity of penetrating Virtual Glass through the use of a transducer that was a feat deemed impossible as nothing was able to penetrate the alien substance.
Zo'or made use of the gun when he took possession of a comatose Human host called Scott Pierce and used his body in an attack at the Taelon Embassy. The discarded CD-57 was discovered by Liam Kincaid when Zo'or/Pierce left it behind. (Episode: Through Your Eyes)