NO2 upgrade module (0-520 ppm 0.1 ppm res.)$1,974.00 For Testo 350 and Testo 340 – NO2 upgrade module (0-520 ppm 0.1 ppm res.) Call us for a quote Product Model: 0554 2200 NO2 upgrade module (0-520 ppm 0.1 ppm res.) quantity Add to cart SKU: 0554 22002 Category: Testo Sensors Parts & Accessories Tag: Testo Sensors Parts & Accessories Related products 3.9′ with 13′ stainless braided TC lead 8 pin connector0 out of 5 Read more Self service replacement CO measuring sensor – 325-1 & 325-3 only0 out of 5 $219.00 Add to cart NO low replacement sensor (0-300 ppm 0.1 ppm resolution)0 out of 5 $868.00 Add to cart