Just found a post in a forum and I think it is an easy mistake to make so I am mentioning it here.
Harman makes the direct positive paper in a 4x5 size. The sad truth is that if you are planning to use this paper with a 4x5 camera and 4x5 film holders you don't want the 4x5 paper.
What you do want and what Harman also makes is the 3.9x4.9 sized paper.
Make sure you make this clear when you order. I was almost shipped the 4x5 paper myself.