These neon waterproof window pens are great as a sign marker pen. Writes on nearly anything...GLASS, PLASTIC, METAL, STONE, ACRYLIC, CERAMIC! Stays on in the rain, but easily removes with most window cleaners! A neon marker with a chisel tip for fine to medium writing width gives you lots of control. Colors include: Red, Green, Orange, Yellow, Blue, Pink, White & Black.