From Halopedia, the Halo wiki
The Forerunner Hybrid Kit is a group of equipment using classified Forerunner technology from Requiem. It was developed for highly experienced Spartan-IVs by the Office of Naval Intelligence.
The kit includes the following equipment options:
‘Imprint’ LightRifle weapon skin
This is also the name of the bonus content from the Halo 4 Console Edition on the marketplace.