Use superstretch sewing machine needles for sewing thin leather and in overlocking machines. The needle is suitable for use with thicker threads. Also for sewing lingerie or bras, as the special blade design helps to prevent needle breakage
Available in size 90/14 and 75/11
System HAx1SP
Easily identified by the white band below the shaft of the needle
 
Is choosing difficult?
In this PDF we have explained the combination of fabric, threads and needles: 
Thread and needles user table
TIP: a needle kan work for 8 hours, afterward it is blunt and needs replacing.

That does not mean that you have to exchange the needle after one day. Look at it this way: if you would push the pedal and keep it sewing for 8 hours straight the needle is blunt 
Easiest way is to insert a new needle in the machine when starting a new project...