How to check if a product is authentic Apple product or not?

I have purchased an Apple 3.5 mm to Lightning jack for my iPhone. Since the jack was discontinued, I couldn't find it with Apple, authorised resellers or any major retailers. However, I stumbled across a website which I never heard off offering to sell the product for the same price as Apple and ordered it. Now, everything looks genuine so far but if I do receive the product; are there any checks I can make just to make sure it's not a fake since I know fakes can affect sound quality.

Here's the link.

Thank you!