This one on Amazon: https://www.amazon.com/gp/product/B001PDGFR8/ref=ppx_yo_dt_b_asin_title_o01__o00_s01?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B001PDG

This one on Amazon: https://www.amazon.com/gp/product/B001PDGFR8/ref=ppx_yo_dt_b_asin_title_o01__o00_s01?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B001PDGFR8/ref=ppx_yo_dt_b... Looks like they're out of stock now, but it has a big label on the front that says co2meter.com, so you might want to check there. I am not affiliated with that company.