Very similar numbers here for an S2+ compared with the S2+/18350, both from Simon.
Both pills seem to have 22x1.25 (mm) threading, but the S2+ pill has 21.75mm outer diameter while the S2+/18350 pill has 21.90mm outer diameter (accuracy is only 0.05mm here). So difference in OD is 0.15mm which equals .006”. But the threading pitch seems to be the same.
So the S2+ pill can be screwed into the S2+/18350 head (feels slightly more wobbly but sits tight in the end) while the S2+/18350 pill won’t fit the S2. Same with head and body, S2 body fits the S2+/18350 head but not vice versa.
Simon was asked whether the S2+ series hosts parts are interchangeable and he could not guarantee it, due to different S2+ batches.
@WWEFANS
Well done so far, I’m highly interested. All depending on price, of course - but I like the idea of a quality host which can use all three sizes from 18350 over 18500 to 18650. I’m a great fan of the 18500 as well. A good IMR 18500 is only 15mm longer than an 18350 but has about twice the capacity and can deliver 3+ ampere without batting an eye. Compared to 18650 lights it’s ~20mm shorter (most 18650 lights fit protected cells) and this makes 18500 far more pocketable.
The tube length of the S2+ is 48mm, by the way, threads ignored.
Way to go 