From D&D Wiki
|This material is published under the OGL|
Price 12,000 gp; Aura moderate divination; CL 8th; Weight 1 lb.
This sight can be attached to a single two-handed firearm. When this is done, the sight becomes part of the weapon, but can be removed from that weapon with a full-round action. A firearm wielder using a firearm that has this sight can choose to spend a full-round action to either locate an invisible creature within line of sight or make a single shot that ignores the invisibility of a creature that she knows is in the area.
Cost 6,000 gp