Co2 Magazine piercing valve part?

[SAW]

Can someone tell me what the small round gold parts are in this Co2 magazine piercing valve?
I have three Co2 AA 1911 mags that all expel the Co2 as soon as loaded with a cartridge through the piercing valve and none of them have this part? Do I need it?
Thanks.

[Daveoc33]

Forgive me if I'm way off here, but that's a piercing valve looks like its for an action army aac21 (sniper rifle). I didn't think action army made a 1911. Are your leaky mags from an army armament 1911 instead? 

 

I've no idea what the gold bits are. 

[Enid_Puceflange]

The gold bits look like some sort of filter to stop crud getting into the system? Looks a bit like a metallic scouring pad?

[MadMole]

Thats a sintered filter not a piercer