This Next Service Due Sticker is made of a durable and clear static cling plastic. After a vehicle has been serviced, place this sticker on the window. You will then be able to fill in the suggested date or mileage for when the next service will be due. Label size: 2x2 inch. The reason why the static cling sticker was dropped: 1. Because the surface is dusty or not clean, there is a lot of space inside which causes the static cling sticker to fall off. 2. The surface is not mirrored or windshield, such as walls, frosted glass, etc., which are not mirrored, generally cannot be attached. Because electrostatic stickers need to be tightly attached, they must be mirrored.