MSA Altair 4XR Gas monitor kit The MSA Altair 4XR is now fitted with Bluetooth so that you can remotely view the readings on your own Android device. The waterproof and shock rating on the 4XR has also been improved compared to the MSA Altair 4X. As a bonus to Sydney Safety customers, we also include a second charger - for your car worth $340 plus gst at no additional fee Gas monitors are not only expensive to buy, but also expensive to run. Every 6 months you are required to have the unit calibrated at a cost, plus most units come only with a 2 year warranty, so when a sensor expires you are up for the cost to replace it. This gas monitor kit from MSA includes everything you need to calibrate the unit yourself, plus the Altair 4XR comes with a 5 year warranty covering all sensors. if you are making a purchase for long term use, then this should be your choice. Some companies insist on daily bump testing. The Altair 4XR actually indicates on the main screen that the unit has been bumped within the last 24 hours. Plus the Altair is waterproof and dustproof.