Very generalized response.
Amazon has a great selection of RV supplies. Other retailers do, too. Amazon is a great place to start your hunt, find the item you want, and then do a general search by brand/model.
eTrailer is another great source, but their site isn't as slick as Amazon. That's why I suggest you start there.
CLICK:
RV propane CO detectors They even sell your brand with prime shipping for $68.
Obviously, the abundance of choices requires that you pay attention to things like dimensions, etc. if you plan to find an exact fit.
I mostly posted this to point you to Amazon for almost anything for an RV, from electric tongue jacks to potable water hoses, to, in some cases, replacement taillight fixtures. Often times you can save a LOT by not buying manufacturer replacement parts...which, by and large, are off the shelf stuff they simply buy in bulk. And if they resell to you, the markup can be nuts.
My RV microwave bit the dust, and I bought a perfect fit replacement of another brand through Amazon for far less than I would have paid a dealer.