From designer:
I am an enormous Snape fan. I am firmly in the Snape-is-good camp and therefore I like to express this at various fannish activities with a “Trust Snape” armband. My original armband was sewn at the last minute from scrap black cotton duck and written upon in white nail polish. I lost it when I moved.

I wasn’t about to let that stop me from wearing a “Trust Snape” armband to the book release (not least because it’s entirely possible--though in my opinion highly improbable--that this may be my last chance to wear one in good faith), so I’m in the process of making a new one with the leftover green and silver yarn from the stripes on my Hogwarts sweater vest.