Once you discard the plastic nozzle, is there a threaded metal cap to use as a seal?
Yes indeed there is. This is the best feature of the Blitz can. The cap is heavy steel with fine machined threads and an O ring that can be easily replaced. It screws into a steel ring in the can.
This photo shows the metal cap stored under the handle. This is how they are sold.
This photo shows the metal cap screwed in place. The price is an error. These cans are listed elsewhere on the Amazon site for $50. The bad reviews refer to the plastic nozzles. I explained above where to get a metal one. (Thanks again Ao.)
This cap keeps the liquid gasoline and vapors inside, and the can is heavy gauge steel so it is very hard to puncture. As long as the gas is contained you are safe from explosion. It is important not to over fill the can. A little below the opening is fine. This allows for compression of vapors in the upper part of the can. I’ve had it in the shade at 110 degrees Fahrenheit with no problem. Direct sunlight in high heat might be pushing it, but probably okay. You can lay a long screw driver across the cap and engage the lugs sticking up to get the cap very tight.