For Singer 201 accessory shopping, one concrete starting point is the bobbin: Singer lists model 201 for its Class 66 metal bobbins. That exact listing is more useful than a promise that a bobbin fits all vintage machines.
Keep the complete designation from your machine and its instructions, including any suffix. Then check each accessory individually. A supported bobbin does not establish the fit of a presser foot, needle plate or other replacement component.
Buying the correct bobbin
Look for an explicit Singer 201 match and the specified Class 66 metal construction. Singer's bobbin guidance distinguishes Class 66 from Class 15 and Class 15J, and distinguishes metal from transparent versions. Do not replace one with another because the bobbins look close in a photograph.
If you have a known-correct bobbin, label and retain it as a sample. Compare the replacement reference, material and intended model before winding it. Confirm the pack quantity separately; a listing photograph showing several bobbins does not necessarily tell you how many are sold.
A bobbin holder or case is a different item from the bobbin itself. When seeking a repair part, describe the actual component and provide a photograph rather than requesting a general “bobbin replacement.”
Choose feet for a specific job
Think about what is difficult in your next project. Stitching close to a zipper, maintaining a consistent patchwork seam or controlling a narrow hem may justify investigating a dedicated attachment. Use those tasks to narrow the search, then ask whether the exact attachment supports your Singer 201.
For every candidate, check the mounting arrangement, holder, any adapter and the permitted operation. “Low shank” alone does not answer those questions. A snap-on foot and a screw-on attachment can require different fittings even when both appear in a low-shank category.
With a used attachment set, request photographs of the individual pieces and their references. Check that the instructions belong to the attachment being offered. A familiar storage box is not enough to identify its current contents.
Follow the machine's needle diagram
Use the needle system specified for your exact machine, then choose the type and size for your fabric and thread. Follow its insertion and threading diagrams carefully. In particular, do not apply a general instruction to put every needle's flat side toward the back; installation directions must come from the correct manual.
When trying a confirmed attachment, follow the machine and attachment instructions for setup and a slow test on scrap fabric. If the needle catches a foot or plate, stop and recheck the combination. Changing tension will not correct a physical clearance problem.
Build a small, identifiable kit
Start with correctly matched bobbins and needles, the attachment you need for the current project and the tools specified for routine care. Keep a note of references that work on your own machine. That record is more useful at the next purchase than an unlabelled box of similar parts.
Accessories should not be the first response to an unexplained mechanical problem. Use the manual's cleaning procedure and seek a service assessment when a correctly set up machine still does not sew as expected.
For a specific replacement question, contact Sewlume with the full Singer 201 designation, the candidate reference and clear photographs of the existing part and fitting.