The OTs-128 is a belt-fed machine gun chambered in 7.62×51mm NATO, using proprietary belt links. The OTs-128 is striker-fired, full auto only, and has a rotating bolt.
OTs-128 uniquely feeds from the bottom and lacks a feed tray or a feed tray cover.
The folding stock rotates upside-down when folded, allowing it to be used as a carry handle and not interfering with the ammo box to remain attached.
A similar Russian machine gun chambered in the prototype 6.7×51mm cartridge exists, and is designated as the OTs-124.
The belt box of the OTs-124 appears to take on some of the roles of the feed tray cover.