XSense Radon Detector sells on Amazon. I think the price is very good. Please read some of the reviews and see people thought of the product.**If you’re not sure whether to buy, add to cart, and you can come back to it later!**

Pay Once, Gain More: You can enjoy up to 999 days of precise, no-lab-fee radon tracking; get trusted results in just 24 hours, with accuracy reaching 95% after 7 days or more for long-term peace of mind and a healthier home Small in Size, Big in Convenience: Designed with a 3.6″ 3.2″ 3.0″ size, this radon detector is compact and portable; place it anywhere in your home for radon monitoring; 2-year battery life means no charging, no maintenance, and no worries; support switching between pCi/L and Bq/m units