Bruce, when I got my Adler it came with small black spacers that were numbered #160, #180, #200, #230 and #250. These are spacers for those needles. While I don't change them all the time for every size needle I use, I do if I swap from a #160 to a 230. I mostly use #200 and that seems to handle most jobs very well with no sewing problems.
Tony.