I was wondering if the 1.4 or the 1 is what I should be using for dbl tray and possibly a weight?
the shorter will work with the tray. the longer with the tray and weight combined.
for just the double tray the 1 is sufficient but if you add the weight you will need the longer knob
You'll need the longest one (1.4)
I have all three knobs
1 attachment (tray) =use smallest knob (1)
2 attachments (tray +weight) or (2 trays)= use the middle one (1.25)
3 attachments (2 trays + weight)= use the longest one (1.4)
Use the longer of the two for a double tray. The shorter one will not be long enough to go through both and properly engage the housing.
I used the 1.4 (I think) with a dual tray to hold a weight. I sold that set so I can't check.
If those are the two sizes, you'll want the 1.4" for dual trays.