The size 3.5 is a little smaller than the factory needle for your machine. Perfect for smaller threads such as Superior’s Sew Fine(tm) or Glide ™. It makes a smaller hole which can be an advantage on batik fabrics. It will have a little more gap between the needle and the hook point, so if skipped stitches occur, change back to the regular size 4.0 needle.
These are SHARP needles (designated R on the package) for regular quilting on cotton and batiks.
This is the pack of 10 needles.
(image is of the 4.0 size needles but just because I was too lazy to photograph all the different packages)