Although often marketed for nitrous oxide system tuning, and sourced from the HVAC trade (they are gas furnace service tools sized in American Wire Gauge), they are probably the best motorcycle carburetor jet sizing tools available. Yes, there are actual jet drills out there, some by Weber, others from all over. But none match the usefulness of this set. Unfortunately, as with many things, the price has more than tripled in the years since I bought mine. By the way, to be clear, I am not advocating drilling jets. I use these alnost exclusivle for sizing jets, that is, making sure they are the size they're supposed to be. Non-Honda jets in particular are often not correctly sized and many in-use jets can be observed to have been drilled.