What Does Suffix "-M" Mean on SST1M-M?

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:

There’s also another pack type for the SST1M version, SST1M-C, that comes in 100 piece bags