Skins from The Cache Collection are not obtainable through the weekly drop.
The Cache Collection is a Valve-made collection of CS:GO skins introduced on 8 August 2014. The collection consists of 0 consumer skins, 6 industrial skins, 5 mil-spec skins, 2 restricted skins, 0 classified skins, and 0 covert skins.
The Cache collection would drop to players who held an active operation pass for the duration of operations Bloodhound, Wildfire and Hydra. Skins from this collection have not dropped since the conclusion of Operation Hydra.