Never lose your pen again! This is exactly what I wanted! A pen case that attaches to your planner Pen case for attaching to your planner Attaches perfectly with rubber and Velcro. Solves the problem of: Pens getting lost in your bag, Falling out of your planner even though you put them in there, And other such troubles. Holds 3-4 pens. Compatible with planner sizes from approximately 19 to 23 centimeters.