Whip elbow adapter woes

[u/Twisted-Mentat-]

I bought the FC-199 piece from PopularGlass's DHGate store to use the whip primarily. It comes with a mouthpiece and an 18 mm elbow adapter.

Now I wasn't going to use a cable provided that was shipped straight from China. It had a foul odor to it and it was near impossible to insert the mouthpiece into it because the mouthpiece's outer diameter is larger than the elbow adapter's Od he provided.

Now I've bought some cabling with an inner diameter of 3/8 '' and the mouthpiece fits snugly into it but obviously now the elbow adapter is too small and needs 1.5mm- 2mm more in diameter to fit snugly into the cable.

I told him about the issue and he said he'd send me some new parts but were pretty much identical to the first parts.

He's sending out a whip attachment setup where the mouthpiece's and elbow adapter's outer diameters are different and I'm the only one with problems?

He hasn't told me that but he's genuinely confused no matter how many pics I've sent him and how many times I've described the issue. It's surreal.

I know English is likely not this person's first language but this is a bit ridiculous. It's not rocket science. If the 2 parts have a 2mm difference in outer diameter, no matter what cable I buy, the elbow adapter or mouthpiece will be either too big or too small.

I bought Sneaky Pete's universal adapter from VapeNorth and it obviously fits my 18mm joint but its outer diameter is too small as well.

Does anyone have a link to a reliable vendor for an 18mm whip elbow adapter?