Magpul just released 4 new M-LOK accessories.
M-LOK Rail Sections, Polymer: As you might have guessed from the name, these are rail sections made from polymer. They are available in 3, 5, 7, 9, and 11 slot lengths.
M-LOK to MOE Adapter Kit: This is likely the most interesting product of this release. These adapter plates are customizable for length and used to adapt the larger M-LOK holes to work with legacy MOE accessories. So, if you are sitting on a pile of parts for your old MOE Hand Guards but want to update to the new MOE SL Hand Guard, you may be able to use these to avoid buying all new accessories.
M-LOK Cantilever Rail/Light Mount, Polymer: This is just like the aluminum version but made from injection molded polymer. This one hurts a little because I just bought one of the aluminum ones last week and the less expensive polymer version would have worked just as well for my needs.
M-LOK T-Nut Replacement Set: If you break/mangle/lose/accidentally swallow your T-Nuts, you can buy replacements.