What is this 858 piece for ?

[joe n]

Can anyone tell me what this part is for it was included in an 858 and NEA handguard i got thanks

 

[Lobster_pot]

The bottom piece and piece on the right are used to couple two mags together.

Not sure about the other thing on the left

 

[joe n]

Oh man, thank you. I never would have figured it out. Now I need to google it lol. Thanks again!

 

[rdavidson]

Left is a compartment for you fab defense pistol grip
Right is a mag coupler