Some Sensata-BEI Sensors encoders will have a model number(M/N) and a part number(P/N) listed on the manufacturer label. The model number is the descriptive number describing the specifications of the part. The part number is what Digi-Key uses to order the part from Sensata-BEI Sensors.
When making a non-catalog request to the manufacturer, Digi-Key will need both numbers from the manufacturer label. Below is an example label from part number 1724-01002-9364-ND.
01002-9364 is the part number. H25G-SB-2500-ABZC-28V/V-EM18 is the model number.
Older parts, the part number can start 924-xxxxx-xxxx. The 924- is no longer used and can be dropped from the part number.