Having the female locked in this position gives 100% control of the depth, speed & duration of anal sex act to the male. While it allows the male unrestricted anal penetration, it also offers a clear & impressive view (for a mirror / webcam / friends / ex-husbands) of the relentless ass pounding taking place.
With this position being quite popular in the mid 90’s, the Cox Knot (or Cox Lock) is now becoming fashionable again in the pornography world as a “signature position” by Porn Stars such as Sasha Gray.
"Nice One! She'll be shitting cum for a week!"