Replacement Carbon Monoxide (CO) Sensor for the following instruments: GX-2003 GX-2009 Gas Watches OX-01 Single Gas Monitor GX-2012 Multi-Gas Detector [custom1] SKU; RKI01-ES-1821 Product Weight (lbs.); No Weight (lbs.); 0.5000 Brand; RKI Instruments MPN; ES-1821 UPC; No BW Sensor; No BW Parts; No Accessory; No Price; $130.00 Color; No [/custom1]