How to get the VAIIYA SA1216 skin?

I saw somebody use an SA1216 with the same skin as the revolver that was given out for the first set of challenges this season, but when I went to try and buy it, it wasn't there. Is it some exclusive or am I just tripping and it wasn't the SA (tho I'm pretty sure it was)? I have the sponsor maxed out, btw, and I only got the Cerberus skin.