What does the suffix “-M” mean on Panduit SST1M-M?
The suffix “-M” designates a pack type of 1000 pieces per bag.
SSTxM is the core part number that includes six different versions of cable ties:
http://www.panduit.com/heiler/PartDrawings/SS_5550_SHT1.pdf
There’s also another pack type for the SST1M version, SST1M-C, that comes in 100 piece bags