Size 65/9

These needles are meant for Coverlock and overlock machines for working with jersey fabrics. They are covered with a chrome coating which makes the needle smoother and better suited for knitted fabrics. The letters CF stand for Chrome Finished

Sewing machine needles by Schmetz are world renowned for excellent quality.
These are slightly longer then universal needles and are used in Coverlocking and Overlocking machines. 

See the owners manual of your machine for the correct needles...
 

Have trouble choosing?
Find an overview for the combination of fabric, thread and needles here: (dutch) 
Garen en naalden gebruikstabel

TIP: a needle has a working life of 8 hours.

That does not mean you have to change your needle after one day. It more like this: If you press the pedal of your sewing machine down and hold it down for 8 hours straight, then you need to change the needle.
The easiest to remember is to have a new needle every time you start a new project