It is an adapter to be attached to the slot on the side of the M-LOK standard hand guard in combination with the Surefire M300 and M600 flashlights.
The flashlight will now be located at an angle of 45 degrees.
It corresponds to the following flashlights.
・ Surefire Scout Light M600 & M300
・ MODLIGHT PLH & OKW Weapon Light
・ Arisaka 300 & 600 series
・ Streamlight PROTAC rail mount 1, same 2, HL-X (without laser)
・ OLIGHT Odin