These are the ones I have used.

I have tried the 10 and 5 ml, but they have other options.

I always put plumber's tape on the threads just to help ensure they don't leak.

I have had very good experience with these so far.

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https://www.amazon.com/gp/product/B07DX4YLW8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1