It looks like aluminum, but it's plastic. It is thought that durability will be low.
It arrived rather quickly considering the pandemic. I ordered both adapters. It took me some time to understand how it all worked. I expected the butane fuel to move between canisters a lot more quickly. It is rather slow so be patient. It is also recommended to put the receiving canister in the freezer for 10-15 minutes before transferring fuel. It is a good idea to weigh the canisters before and after to ensure they are not overfilled. Mark the canisters as 'refills' (use an 'R' on the bottom) and the number of times. I learned all this from a few blogs and videos.