Using these Pica 4020 leads is super easy. Just pick up the lead from the convenient plastic box and start marking on your desired surface. Whether it's dry or wet, glossy or rough, they'll work great. If you use them on a glossy surface and want to remove the marks, simply grab a damp cloth and wipe it clean. Since the leads are already sharpened, you can start using them right away. When it comes to storage, keep the red and yellow leads in a place where the temperature stays below 30°C to maintain their quality. And there's no need to worry about frequent maintenance; just keep them in the plastic box when not in use to keep them safe and ready for your next project.