These are still the most common "industrial" size (system or class is proably a better term). My Phoenix takes these needles, it's a domestic machine from 50s. There are lots of needle systems, industrial or not, but they if someone just sais "industrial" this is the type. 1738, DBx1, 16x31,..., are the same needles. I have no idea why these needles are listed under at least six different numbers.