I ditched the big green covers because I wanted a more subtle reminder that I was suckered into nitrogen snake oil. Actually it wasn't listed anywhere on the truck invoice so it was probably buried into that $2,500 "dealer protection package" that took a few minutes to negotiate down to $300.I doubt you are putting these on your Formula One race car so stop reading this review and search Nitrogen fill in normal vehicles. You'll be topping these tires off with Costco air in no time. Then buy these caps to impress your ignorant on the subject friends. Don't forget to check your tire pressure monthly.