Blackwing x ScrawlrBox Replacement Erasers
Blackwing have always been known for their iconic, replaceable, square erasers and now there's a Scrawlr version. To replace simply slide the eraser and clip out of the ferrule, remove the old eraser from clip and place in the new one, insert the new eraser and clip back into the ferrule and voila, you're good to go.
Set of 10 Erasers.