If you want to find such companies, you should check whether the company is affiliated with a local Better Business Bureau or has any other certification.
When you are ready to begin the installation process, start by using the internet to find a qualified professional that has experience installing and designing SOD systems.
First, all three companies were affordable and offered reasonably priced sign services. Some of them were offering free sign installation service, which I really appreciated.
And a radon testing kit. You should also consider having the items installed by a professional, especially if you have children or pets who may be affected by the fumes.