The difference between part number B**B-PNISK-1A(LF)(SN)(F) and the same without the (F) suffix is the wafer material. It is the part with the (F) that can only be purchased. It is the same glass-filled PA66, UL94V-0 material as called out on our data sheet online: http://www.jst-mfg.com/product/pdf/eng/ePNI.pdf