C23810 Deck Cross Belt for both left hand and right hand (38 inch/40inch) decks.
For G-N40 series and RM 38 decks.   
OPTION- to Choose USA Made Aftermarket quality belt is is a great belt and fit for this application. We use the aftermarket belt here often and are very happy with them. Or You Can choose OEM made in Mexico for a up charge.
 
OPTION- Add Replacement Tension spring for proper belt performance and longevity!
 
This is the inner belt connecting the spindles on the mower deck.
**Picture shown is a stock image of a belt for a Case Ingersoll, not necessarily the belt in listing**