accessory advice

Hello, first post and new to both solar and bluetti. I have a pair of AC300s and am looking for a good source for accessories such as cables. Not having any luck finding the communication cable required to link them for split phase operation on the bluetti site or amazon. Is there a good reputable third party site that caters to this? thanks in advance for any advice.

Do you need this communication cable? According to my search on the official website, it is in stock.