Significant sale on Aranet 4 CO2 monitors

COVID-cautious folks:

Carrying a carbon dioxide monitor helps me check how safe the air quality in a space is, and lower or raise my cautions accordingly. (Details and photos.) Super useful.

I use and like the Aranet 4 CO2 monitor. The Aranet 4 is usually USD$249. It's on sale, direct from the manufacturer, till September 17, for $184.35, with free shipping in the US.

Or from Amazon for $197. (Might be today only - Sept 7th.)