try these links (take close photo of the white knob (pull to

close)

https://diy.stackexchange.com/questions/162033/how-to-remove-this-toilet-supply-line-that-seems-to-have-no-nut

https://terrylove.com/forums/index.php?threads/pex-shut-off.69987/

https://accortechnology.com/

Google photo search can match similar photos. 

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