Guinevere Hand Pump 

Guinevere inflatable drums require very little air, so it’s very easy to over-inflate them with a compressor. The compressed air system must be able to deliver totally dry air, otherwise moisture will cause rust on the internal steel parts, and will interfere with the airtight seal of the interior valve. 
The best way to inflate the sanders is with King Arthur’s Tools Guinevere small hand pump, which allows you to feel the softness of the bulb while you are pumping, giving you the ideal drum softness for the grit being used. The best pressure is as soft as possible while still keeping the sleeve from moving on the drum.