I think the US Marines or Army uses it on their DMR rifle, not sure which one though.
All of them, Army, Marines, Navy, Coast guards, etc. All have a different model varying in buttstock, color and accessories. At first they took only the standard barrel, then medium and now heavy.
In Canada the importer only get that one (pictured). It's a:
-Mod.0: the particular collapsable stock, 8 positions in Canada instead of 6 in the US
-Chopmod: short handguard not covering the gas cylinder
-5 screw handguard/top cover allowing medium barrels
-in black only
One could make it lighter by removing the side and bottom rails and replacing the buttstock with another Rem870 compatible. The Sage Mod.1 use the AR15 collapsing stock but it's not available here.