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The smallest size is still made, Mouser, RS & Farnell have both PX0646 (straight) or PX0430/SE (right angle), these both have cable grips.
Avoid old stock as they are made from quite brittle plastic and avoid the low-voltage version that can do undone without tools.
The larger size is no longer made AFAIK, I have seen a right angle version with cord grip too.
These are used in some old audio gear and fetch high prices as a result.
David