Ahh, ok. Gas detection sensors are typically built for specific gases, but your manufacturer seems to build generic sensors. Don't forget that propane is heavier than air, once you start mounting them.
"The Billing Address counts as t sets the sales tax for that address."
I've found it's the service address that determines the sales tax. We are full timers, and over the past few months have been in several states. I called DISH to ask about the various sales taxes being charged, when there should be none as our billing address is Florida where no sales tax is charged. The account rep didn't know, and put me on hold while he checked with someone. He came back on the phone and told me it is the service address that determines the tax rate. During the times that I was charged a sales tax, my service addresses were mostly in the state where the tax was assessed for most or all of the billing period.
Florida isn't the only state that offers health insurance plans with nationwide coverage. As mentioned upthread, Blue Cross in Michigan has a PPO plan. And I know that Blue Cross offers a PPO plan in Maryland that has a nationwide network.
That is not health insurance. It's an indemnity plan. They are not the same thing, and don't even consider an indemnity plan as a substitute for health insurance unless you really understand what it is.