Wraith transporter generator
From The Stargate Omnipedia
Diamond-shaped unit located inside the rear ventral portion of Wraith Darts. The device is contains the firing mechanism which releases a culling beam. It is attached to a thick cable which can be extended several feet from the main body of a downed Dart.
KEY EPISODE
Duet - Atlantis scientists remove a transporter generator from the body of a crashed Wraith Dart to see if they can find a way to access its materialization mechanism.