Ultrafine makes Extreme 400 in 120 and 35mm styles. I tested them both and find out there is some differences.
Ultrafine is store that sells its own line of Black and White films in 35 and 120 in ISOs of 100 and 400. You can buy directly from their website or one of their re-sellers. In the past year I had the opportunity to purchase a bulk pack of the Ultrafine Extreme 400 first in 120 then shortly after in the 35mm format.
My first shots in the 120 format were a bit over-exposed by my Holga on a sunny Sunday morning, but the images were clear and low grain.
And in the Southern Hemisphere another Lomographer tried it out with a Diana F+.
Satisfied with the results I purchased a bulk pack of the 35mm in 36 exposures.
Taken with Canon AE-1:
I also ran it through the Sprocket Rocket:
I am not sure if these really are the both the same film stock material. I find a more noticable grain in the 35mm format, but I have read that the nature of medium format film causes less grain even at higher ISO. Which is a either a desired result or an unwanted one, depending on the photographer.
I would recommend the 120 format the most. Its negatives were decent to work with and the grain is nice for its size. The tones are also clear.
My thanks to adam_g2000 for allowing me to use some of his lomographs.