Japanese machinery and maintenance enquiries often place strong emphasis on drawing control and exact part identification. For NM couplings, that works well with a model-specific approach: keep the model, bore, keyway and elastomer requirement explicit.
Use the drawing revision as part of the RFQ.
When a shaft or coupling detail is controlled by a customer drawing, include the revision and state which dimensions are mandatory. If the enquiry is a replacement, note any old marking but still provide measured shaft data. Similar-looking couplings should not be treated as automatically interchangeable.
For compact machine layouts
Check D, D1, L and the required S gap against the surrounding cover or machine frame. If the machine uses a high running speed, compare that limit before moving to a larger NM size just to gain bore capacity.
