Hi, I have three of this style of adapter plug, the first one came with a Nook tablet, which I bought in 2013, and which I now use for charging my Walkman mp3 players and a couple of small battery packs, which can be used to re-charge mobile phones when out and about, plus a couple of portable speakers, but not all at the same time of course. The second one I have is for a multi-voltage power supply, which claims to be able to be used worldwide, which I got from Maplin electronics a year or two before they closed their stores.

The third one I have is for an Asus E21OM laptop, which I bought just last July 2022. Only the Nook and the Maplin ones have a locking mechanism, the Asus one just snaps and unsnaps into place.
Regards Nick.