Dear Ms. G:

You wrote:

In the phrase “The non-self-tapping screws are available.” Should there be two hyphens? One? I can’t figure this out.

Thanks.

“Non-self-tapping” is the best way. The prefix “self” is normally hyphenated. “Non” often is when it is used in a nonstandard or coined word as it is here. “Nonself-tapping” would be acceptable, but it is not as clear. (Does the screw tap a nonself?)

I Hope this helps.