Question about Philips Sonicare DiamondClean 9900 Prestige

The Sonicare 9900 Prestige offers more smart features, improved pressure control with visual warning signal and a longer battery life than the DiamondClean 9000. It is quieter, has a higher water protection class (IPX7) and has five cleaning programmes, while the 9000 only offers four. The 9900 Prestige can be controlled via an app, the 9000 directly on the appliance.