We loved the rugged reliability of the Aranet4, but we were very interested in making a wearable sensor. The Airship is based on a Sensirion SCD-41 photo-acoustic sensor about the size of a sugar cube paired with a LilyGo dev board and a small lithium polymer battery. The LilyGo has an attractive RGB screen and built-in Bluetooth. The whole unit is about 1/3 the size of an Aranet4.