Example part numbers:
B10B-PADSS (LF)(SN)
B10B-PADSS-1 (LF)(SN)
Compared to...
B10B-PADSS-F (LF)(SN)
B10B-PADSS-1F (LF)(SN)
The difference is the raw material resin used. Without the "F", it is glass-filled PBT. With the "F", it is PA66.