eureka fluid film rustproofing
Unfamiliar with this product. It seems rustproofing/undercoating is not too popular as folks just "buy a new one".
We found a local body shop that did undercoating and we did all the prior masking and taping, and removal. This ensured a good job.
You will be far ahead, if you live in the east to have it undercoated. Many states are now "pretreating" roads with salt brine. You can be driving in dry conditions and be subjected to the dust and spray.