Highlighters are invaluable study aids and reading tools, but nothing undermines their effectiveness like accidentally highlighting the wrong thing. With FriXion highlighters, however, that's no problem! Simply use the rubber "eraser" tip at the top of the highlighter. The ink disappears cleanly, and there are no eraser shavings. After trying a FriXion highlighter, you'll wish every highlighter you owned was erasable. These standard FriXion Light highlighters are eco-friendly too, made of 87% recycled materials. This set contains 6 colors: Pink, Orange, Yellow, Green, Blue, and Purple. FriXion highlighters use a special thermo-sensitive ink that turns invisible when rubbed with the built-in friction "eraser." The ink disappears cleanly without using up the eraser or creating any dust or smearing. The ink will also disappear if exposed to other sources of heat or friction, so JetPens advises against using it on envelopes or leaving anything marked with FriXion ink in a hot car. Like magic ink, erased FriXion ink reappears if placed in a freezer or otherwise exposed to temperatures below 14° F (-10° C).