The DZP MK2 foam dart blaster has a design problem
the screw posts that connect the plunger tube to the slide grip are not supported by any webbing, over time they can crack or show signs of plastic stress.
This part is meant to provide additional support to prevent breakage.
key point, is the front section fills in gaps, such that the lip at the front of the grip can directly support the front of the plunger tube; rather than putting all the force on the screw posts.
The author hasn't provided the model origin yet.