Sorry, I looked for the thread where someone was asking about plugs or caps for male air tool fittings. I do store my air tools, not nailers, but other air tools upside down by the male fitting in an aluminum rack that I bought off of eBay. And, the garage can get relatively dusty. It got me looking for the plastic caps that come with nailers, but they were relatively expensive. Also looked for rubber or plastic vacuum line type caps, but couldn’t find anything reasonable. Long story short, #8 exterior, bugle head screws fit perfectly, had them laying around anyway, and when the tools are stored hanging like I have them, seal off the male intake just fine. If I lose one, I have another couple of pounds as a replacement.