Im not really sure. My friend Michael said last he knew of it jrok builds them in batches for supply and demand. The other weird thing is,Michael builds alot of Superguns,and he recommends jroks encoders the most as far as encoders in the USA goes,but he noted that sometimes he saw varried results with them and the sync cleaners on certain games.
They always fixed the issues with the american games like Primal Rage and Time Killers,but sometimes they caused a slight signal noise issue with some CPS 1 titles,and really bad signal noise on Survival Arts,a Sammy game. He said this tended to happen not too often,so its not a issue with every encoder and sync cleaner hes used from Jrok.
He doesn't even buy them from Jrok he said,he just has a customer order it himself when he is building a Supergun for them,along with ordering all the other parts needed,this way the customer knows what they are paying for exactly. He's built two of my Supergun kits,does fantastic work. I think I have a pic he gave me of a couple of others he did. Ill have to check.