The air pump from Teleskop-Service should not be missing in any accessory case, photo case or eyepiece case. You can gently remove dust from sensitive surfaces with the bellows. In opposite to compressed air bottles, you are ensured that no residues of propellant gas will get on the optics, and the bellows is more environmentally friendly, anyway. Due to the reduction of the inner tube diameter to only 2 mm at the front, a concentrated airflow is generated when pushing the bellows, which blows away any loose dust and sand grains.
Especially when working with CCD cameras, where every dust grain becomes visible as unaesthetic donut, but also when carefully cleaning eyepieces, mirrors or objectives, blowing clear the surfaces prior to cleaning is very important. Never blow on the optics using your lips, as there are always small droplets in your breath which will remain on the optics or even smear over from the cleaning.