Napier VP90 Corrosion Inhibitor.

This remarkable product is used by over 500,000 shooters worldwide to protect guns or any metal objects, either in a gun safe or bag.
Advanced vapour phase action deposits an invisible mono molecular coating on any exposed metal, leaving glass, plastic & wood unaffected.
Anywhere air can penetrate VP90 will protect.
New VP90 now lasts 50% longer and protects a typical 5 gun cabinet
1 cubic metre (35.5 cubic feet) for over 9 months.