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It looks like a co-ax plug. Common type that often carries DC power. However the plastic end ring is not smooth and narrow like the ones I'm used to handling.
It looks like the plastic was heated until it melted and expanded outward. But there's a substantial amount of plastic there, more than would account for normal construction. So I could be wrong and it's supposed to look that way.
The oversize plastic rim looks as though it would make it difficult to yank the plug out of the jack. But then the jack would need to be oversize in order to accommodate the oversize rim. Seems to me it would create loose play.
There also needs to be a strong springy metal tab inside the jack, to make proper contact.
If you are looking for a replacement, an ordinary co-ax plug should suit. They come in a large assortment of inner and outer diameters.