Can I use these for stretchy jersey fabric?

Hi Jessica, Yes you can. Please call the store at 800-442-8227 and ask for our sewing specialist for further details. Thank you Scott

I am using 80/12 needle..what is an 11 needle? Thanks..jc

A #11 is slightly thinner than a #12. It leaves a smaller hole when it pierces the fabric. It is good enough for general sewing and piecing quilt blocks. If you are using a thicker thread (like 50 weight cotton) you may want to stick with # 12s, as a #12's hole is larger and the thread will go through more smoothly. (To give you a slightly better reference, call #12s average and # 14 suitable for heavier fabrics such as corduroy and blue jean.) -- just as an aside, I personally did not like these blue tip janome needles...they were really flimsy and I had three of them break lickety split just using them for general sewing. Given their price, I was not happy about that!

Are these for knits also?

Yes, but not recommended. This needle is actually 75/11. A 90/14 (14) or ballpoint needle would be better for knits.Check out this chart: http://www.sewing.org/files/guidelines/22_115_sewing_machine_needle_charts.pdfI hope this helps.

Nowhere in my Janome sewing machine manual does it explain the color coded needles,does anybody know where i can find information

The Janome 6650 manual has a fabric and thread and needle chart on page 17. You can look online at the manual even if you do not have that model sewing machine.