Yes, I agree with NH Horseman. We've stored our RV for the past 6 years in a huge metal barn in a Kansas field with other RVs and some farm implements. We have used "Fresh Cab" during those years with no rodent problem. Not even droppings, which tell me they truly are repeled by the smell. And it does smell very nice.
Here is the website for the product. Watch the video. It is an interview with the creater of the product.
I order the product online. It does appear to be expensive but works out to around $4 a sachet. Well worth it, if it prevents some costly wiring repair and/or issues while on the road.