Apparently The Blue Part Of The Eraser Was Never Meant To Erase Pen Marks. Here's What It's For - ScoopWhoop
Amazon.com : Pencil Eraser Retractable Mechanical Pen Eraser Green Blue Orange Purple Pink Color Plastic Rubber Aesthetic Erasers for School Office Painting Writing Drawing Drafting 5.31 x 0.39 Inch (15 Pcs) : Office Products