What part is this?

[BigRedMJ89]

Needing help identifying  this part please guys. 
Replacing somethings today 

[Big Dan]

Are you pointing to the air hose?  It goes from your airbox to the manifold to, I believe, assist with warming the engine up quicker.

 

I picked some different sized flex hoses from McMaster-Carr and tested which one fit the best.

[BigRedMJ89]

Yes, it’s a air hose that connects to manifold. 
 

any specific size I should try that worked for you? 

[JustEmptyEveryPocket]

I just removed that from my truck. Its not needed. As Big Dan said, it only helps warm the intake air for the first few minutes of running, then a plate blocks this inlet. So just run it without imo.