3 Packs Plug In Gas Carbon Monoxide Detector, 4-In-1 Carbon, Apartment Product Features ?3 Packs Upgrade Plug-in Combination Gas Carbon Monoxide Detector? Plug and play, easy to install, 4-in-1 sensor, real-time monitoring display and alarm. ?Combination Gas Carbon Monoxide Sensor? Adopting catalytic combustion sensor and electrochemical sensor, real-time monitoring and displaying the concentration of combustible gas and carbon monoxide, with sharper and more accurate sense of smell. ?Temperature?F? and Humidity Sensor?Real-time detection and display of temperature and humidity, let you know the environment in real time. ?85dB Alarm Sound?Combination gas and carbon monoxide detector will alert you immediately when the combustible gas or carbon monoxide concentration reaches the default value. ?Upgraded Design Round Color Screen?Color display with bigger and clearer digital display. ?Application?Combination gas and carbon monoxide detector is suitable for home, restaurant, apartment, office, hotel, petroleum plant, gas station, campervan, etc. Shipping: Shipping is complimentary within the lower 48 US States. We Do Not Ship to PO/APO Boxes, HI or Alaska We Do Not Ship Outside of the Continental US All items ship within 24-72 hours of Payment For large items that require Freight shipping a valid phone number is required to call and schedule your delivery Terms of Sale and Feedback: Feedback is extremely important to us and If you are satisfied with our transaction, please take a moment to leave Positive Feedback. YOUR Satisfaction is our #1 Priority! If there are any issues, PLEASE contact us BEFORE leaving a neutral or negative rating so that we may resolve any concerns. We PROMISE we can make you happy if you give us a fair chance. Returns / Concerns: All items qualify for returns within 14 - 30 days of receipt. Buyer is responsible for return shipping on any item that is not damaged Please be sure this is an item you want before making your purchase. Customer Satisfaction is our TOP priority! All items are IN STOCK at time of listing. Inventory changes constantly and it is impossible to maintain a perfectly accurate count of all items. Please do not penalize us if we have to issue you a refund! Thank You For Your Business!