You can see here they have it at the beginning
Thanks. Thats interesting they have the knurling at the end and also the shank. I thought Koken only had knurling at the end.
Sorry to talk so much about knurling. Other thing to think about is lengths. Snap on extensions are very clever about lengths.
In the old days, extensions were available in sets like 3,6,9,12”. so obviously you can join two together to make one of the others. Snap on extensions aren’t like that. When you join them, you get in between sizes. I’ve never done the math, but you may be able to build extensions every inch from 2-12+ or something like that. The Koken set I just saw online is 32, 50, 75, 125, & 250mm
That said, to be honest, I rarely do that. I’m always good with close enough. But there could be jobs out there where you need something specific and I just haven’t come across them.
SUMMARY
1) I like tight fitting extensions. Don’t love slop in the joints. I’m sure either Snap on or Koken would be more than acceptable
2) Knurling I’ve beaten to death
3) Lengths included in the sets can be important.
4) Last- I think extensions are luxury tools. I have several sets and they do get me out of jams. My opinion: more is better