NZ, there's a tag welded to the prop which fits under the jack head, alternatively the prop is shaped to fit, as on the right in the photo:
https://www.dropbox.com/s/r983aq28my...P2183.JPG?dl=0
WARNING: This setup isn't foolproof. The car may be damaged If the jack is lowered when the prop is not engaged in the head of the jack.
The bottle jack/axle stand combo looks safer in that respect:
https://www.amazon.com/Powerbuilt-64.../dp/B003ULZGFU
See also:
https://safejacks.com/products/the-r...d-by-safe-jack
and:
https://www.youtube.com/watch?v=azkT6mL_tDQ