552i - App-controlled wireless vacuum probe. Use the testo 552i vacuum probe with Bluetooth to measure vacuum wirelessly with speed, ease and precision via just one service port – with no loss of refrigerant. The testo Smart App supports you with numerous intelligent features – for example, you can see the vacuum by simply glancing at the graphic illustration in the app or on the manifold’s display. Thanks to its robust, convenient housing and proven measuring technology, the vacuum probe is compact and reliable when carrying out your vacuum measurements on refrigeration and air conditioning systems and heat pumps.