Supply line for kitchen sink needed

[Jsmallberries]

New kitchen sink faucet has 3 lines, one for filtered water, the product was missing the third supply line.

Can I purchase these locally?? looks like a 3/8" threaded male with 2 washers, see photo.

They included a 1/2" female adapter instead

 

[Dj2]

Post another picture that shows everything.
Do you have installation instructions?

 

[Sponsor]

 

[Jsmallberries]

They admitted they left out the third supply line and included the 1/2" female by mistake. They responded right away, but the replacement can take up to 12 days. I'm sure this is proprietary, since it has those 2 washers.
Below is a picture from their marketing materials, 3 lines included
What about the fact that the supply is copper? Supposed to be for reverse osmosis fed line, not really RO approved?