UU Card Sleeves
From Unstable Games Wiki
There has been some disappointment that the colors of the sleeves weren't exactly as expected, so here are scans of the exact colors. (Note the hex color text is not part of the actual sleeve but only for reference)
The sleeves were available during the campaign for Control & Chaos and though they are not available for purchase yet, were not KS Exclusive and will be available in the future. It has been announced that they will be available for purchase through the Runes & Regulations KS campaign, and soon through the TeeTurtle store itsels.
Also note the sleeves are not opaque, here is a sample of what they look like with cards in them