Well I can’t find any documentation, but by testing it I’d say it just a multidimensional array. If you declare it as TArray FrameBuffer[2], you can’t work with FrameBuffer as an array, but you can work with FrameBuffer[0] and FrameBuffer[1] as separate arrays. I.e. FrameBuffer.Num() or FrameBuffer.Add() won’t compile, but FrameBuffer[0].Add() or FrameBuffer[1].Num() will.