The "K1" identifier in the part number (J102K1CS124VDC.36) is typically a manufacturer-internal sub-code for a product family or revision marker. It may signify: 1. Manufacturing process or material changes: For example, optimizations in coil winding technique, internal connection method, or minor structural materials aimed at improving consistency or reliability, without altering any parameters defined in the external datasheet. 2. Internal standard or qualification code: It may correspond to different internal quality control procedures, lot traceability codes, or indicate compliance with a specific unlisted customer specification or industry standard (even if the datasheet "Qualification" section does not note it). 3. Alternate/Replacement designator: "K1" is sometimes used to denote that this part is an alternate or upgraded version of an original part (J1021CS124VDC.36), representing a version iteration within product lifecycle management. For the design engineer, this difference is negligible, and the parts can be treated as the same. In procurement and production, they should be considered interchangeable as distinct part numbers. However, care must be taken to use only one of the numbers consistently in the BOM (Bill of Materials) to avoid confusion. The price difference ($0.01) likely reflects only the revision update or different procurement batches.