I use LPS-3 Rust Inhibitor. Not saying it's the best available, but it has worked well for me. I picked up 18" of small diameter tubing from a hobby shop that just slips over the red straw that comes with the product. It still creates a good fog and allows me to snake it into various areas of the frame for good coverage. I've never had a bit of rust inside my steel frames even though they get ridden under wet conditions and one is my winter bike on salty MN roads. The bikes do get good care and are stored in a garage.