Where to find air balancer kit

Hello all! I have been rebuilding the forks on my 1984 ZN750 and as I was doing so, I noticed there was a small hole in the side of the inner fork tube (pic attached). From what I could find online, this is meant to balance the air between the two forks, but for the life of me I can't find anything online.

Can anyone confirm my suspicions, and if they are meant to balance air, can anyone point me to a parts diagram so I can get everything ordered in? Many thanks!

No eBay APP ID and/or Cert ID defined in Kunena configurationAll the parts are clearly shown in the OEM parts fish. Where have you been looking?



And BTW, ebay is flooded with those cross over parts...