So I have a serger / overlock machine that has a manual specifying that it uses a needle type called "HA-sp1" needles. Alternatively, they are also called "HAxsp1" and "15xsp1". They're all the same thing.
So I was in a bind because I had no needles for the machine! And I'm on a deadline!! Those needles aren't sold locally, and I don't have a day to spare.
Turns out, the Schmetz company low-key confirmed that their 11/75 & 90/14 "Stretch" needles are very very similar to the HAxsp1 needles.
I tried it, though I was not optimistic. Hours later, no breaks, strikes, or any other funny business! HALLELUJAH!!
Change to the proper needle specification, when you can, but, as a temp, it seems to work just great!
So, to summarize:
All these three needles are literally the same thing: HA-sp1 , HAxsp1 , 15xsp1
The alternative needle if you're in a pinch: Schmetz Stretch needles, size 11 or 14, depending on how heavy your fabric is (11 for light - medium & 14 for medium - heavy).
Happy sewing!