Wow, 13 PCi/L is too high for comfort. Means you need some air moved out of your basement. My kid's house had about those readings and one radon pump fixed it.
My son-in-law had this one for a long time and wasn't happy with the way it worked.
I gave them my
Safety Siren Pro Series3 Radon Gas Detector - HS71512 unit.
They like it because it gives them an instant display short and long term Radon.
And used my old one. Which was accidently dropped by a neighbor and badly damage during the apocalypse.
I borrowed this AirThings, updated the firmware, checked out the app, admired it, and actually got it for Christmas!
I'm really liking this, because it has cellphone alerts (it told me to turn on the heat in the basement). The limits are pre-set by the vendor.
It's comm is on BT, (no WiFi) and it seems to update anytime I'm at home, no need to go down to the basement.