For the longest time I was 100% convinced that base & top coats were a scam and were totally unnecessary. That was until I started using them really extends the life of your manicure. Before I started using this stuff I'd get a chip in my polish within a few days. Of course by the end of the week, there are wear marks on the tips of my nails but other then that my polish is always or at least id 99% intact when I use it.
This is what Revlon says about it: "A great multi-tasking product: it first smoothes the way for nail color, then seals and protects with a hard, shiny, chip-resistant finish •Multi-tasking formula fortifies nails from bottom to top for longer wear •Smoothes nails and prevents yellowing •Seals and protects with high-shine finish •UV absorbers fight sunlight to keep your nail color pure •Patented plasticizers and an acrylic polymer form a shiny, flexible shield •DBP, Toluene and Formaldehyde Free Application tip: Apply one coat both under and over Revlon® Nail Enamel" This costs $7.99 US at Ulta. (I got mine at Shoppers Drugmart - We don't have Ulta in Canada sadly lol) You get 0.5 Fl oz or 14.7 ml.