Several questions have popped up in this discussion. I have the Schmetz chart in a drawer where I store my needles. I also have all of the information from Superior Threads. Uncle Bob is very knowledgeable. I store my needles in a drawer that I equipped with little compartments from a kitchen items. I keep them separated into compartments. I keep a red tomato pin cushion on my sewing table that I marked with a Sharpie with size numbers. It has one or two of the most used sizes. I always know what needle is in my machine because I put a special pin in its place on the tomato. I like the titanium needles. I only throw away a needle if it breaks or if it gets a burr because I stitched over a pin (never on purpose!). I do think using the proper needle is important.