Keycovers are an effective barrier against dirt and dust.  They are manufactured from solid vinyl sheet and offer far better protection than other materials.

They are translucent, which allows you to see if you have left your instrument powered up, thereby preventing accidental overheating.  Keycovers are treated with an antistatic agent, this helps prevent dust settling but more importantly stops a static charge from being developed when the Keycover is removed. Static electricity can damage your software, disks and memory.