Below is a part number breakdown for the RSMF series of Metal Oxide Film resistors from Stackpole Electronics.
For the 3W power (RSMF3), you may see the -C1 suffix code added on the ordering code, such as RSMF3JA20R0-C1.
Normally the RSMF3 is taped at a class 2 (63.5mm) taping width (as the dimension “D” in the image below). The -C1 denotes class 1 (narrower) taping. It’s just packaged at an inside tape to inside tape spacing of 52.4mm instead of 63.5mm.
There is no functional implication for this suffix code.
Applicable Part Numbers