Screen Cleaner Blackboard Eraser Strap For wiping screens of smartphones, Switch, etc. "Nostalgic Blackboard Eraser" transforms into a screen cleaner! [Features] Microfiber is used on the wiping surface, making it sparkling clean with just a swipe. Dustless Nostalgic Blackboard Eraser Available in key chain and strap types. I have kept it stored without ever using it.