Airthings Corentium Home Radon Detector 223 Portable, Lightweight, Easy-to-Use, (3) AAA Battery Operated, USA Version, pCi/L https://www.amazon.com/dp/B00H2VOSP8/ref=cm_sw_r_apan_i_Z53AY3HFBR9FHN1K52SE
Worth every penny.....
Unfortunately it's not the kind that gives you a quick reading, it's designed to take readings over a long.