Hi ladies (and maybe some gents?) I'm looking to add some presser feet to my collection but I'm totally confused. My machine is the Bernina 350PE, and I wanted to get an overlock foot #2 and a blind stitch foot #5. Now there are all of these letters after everything and I can't find just a regular 2 or 5. Do this exist? Can I still use the ones with the letters after? It's all unclear, even on the website. Thoughts welcome!!!