Radiator louver?

[RM125CCF]

I searched and couldnt find much on this just tonight I looked at my radiator and it looked funny because on the right side radiator the louver is there but on the left its missing I know it was on there before because i had seen it. It probably fell off riding when i crashed one time i'm just wondering if I cant find it is it necessary like does it help cool the bike down?

 

[CRguyStan]

I think of the stock ones as sort of two fold, the louvers foremost are there to stop rocks on direct hits, and secondly could help direct the air in. I would say yes you want something, stock plastic, Devol or similar aluminum, but something to save you from blowing a hole in your rad in the woods/track.
Stan