Perfect for my dry-erase acrylic calendars! These chalk pens are black, so they are perfect for showing up on clear surfaces! These liquid chalk markers can be used on non-porous surfaces. It will make your Circle & Square dry-erase calendar pop! Each pen has a reversible tip offering 2 different writing styles in one pen - choose chisel or round whenever you'd like! Wipe clean with a soft cloth or dry-erase cleaner. *they are permanent if used on chalkboards (aka non-porous surfaces)* Product Details - THREE chalk pens included - FREE SHIPPING - 6mm Fine tip - Reversible tip : Chisel or round! - Black