I'm not sure if this product is USCG approved or not as its made in Britain and is CE approved however for the benefit of our non US readers :
We have one of their units installed - its 4 years old now and the sensor was playing up and sensing propane
when there wasn't any - this resulted in the solenoid valve shutting off at inconvenient times.
So being the "rocket scientist" that I am, I decided to tinker with it and install an over ride switch to open the valve electrically from the galley
while a new sensor was en-route to Florida
I fried the brains of the unit as evidenced by a burning smell, some smoke and an alarm
that refused to stop.
Haztec replaced the unit for free!!!...
Now hows that for after sales support on a 4 year old unit?
I had to take a couple of aspirins a cup of tea to quell my shock.
I cannot speak highly enough of the help and assistance provided by Peter Garrod of Haztec.
The unit works well, it has great after sales service
and support - what more can one ask for.
See : Home page of Seath Instruments (1992) Ltd
Note : I have no interest of any kind in that company.