There isn't a number and that's not what I'm worried about, the jets in these NT carbs and the nicer HP carbs from bikeberry should he interchangeable with each other, my new hp carb is running bad so I wanted to swap the jets before I buy a kit to see if it ran better, the NT carb jets have much bigger threading than the 20 dollar HP carbs jet that I have on Amazon, I want to order a set of jets but I need to know what size. On the products Amazon page all it says is that the jet is 6mm big. https://www.amazon.com/dp/B07989QWFH?ref=ppx_pop_mob_ap_share