The size of needle depends on what type of thread you plan on using. Superior Threads has a great site that show you what type/size of needle to what type of thread you need. I generally do FMQing with 50 0r 40 wt. thread. For 50 weight thread you need a 12 needle and for the thicker threads like 40 and 30 you need a 14. I generally use topstitch or microtex needles for FMQing. Go to the Superior site and do some research.