Schmetz Serger Needles ELx705 Overlock sized 90/14. If you use your serger often, you should change the needles often. I usually change between projects.
90 is the metric number, 14 the imperial number (United Kingdom). Usually both are listed.
A 40wt. thread is best with this sized needle. This needle is suitable for medium-weight fabrics such as slightly heavier-weight cotton, polyester, linen, and lightweight upholstery fabric. If your fabric puckers, try a smaller needle, like a 75/11.