In case you forgot, the 49ers are sporting those black alternates on Sunday. We've got some pictures from earlier this summer.
The San Francisco 49ers host the Arizona Cardinals Sunday afternoon at Levi's Stadium, and it will mark the second time this season the team has sported their black alternate uniforms. The team wore the uniforms back in September for their season opener against the Minnesota Vikings. Along with the the black uniforms, the team paints the end zones black.
In case you do not remember what those uniforms look like, here is a photo gallery I put together back in May.