I've been running mostly with the eGo-V V3 Mega and lately V4 updated version of the 1300mah VV/VW usb passthrough while charge type battery with only one loss since first finding the SLB V3s
back in January and in the last month a Canadian vendor with the Green Vaper V4s
. The newer V4s no longer see the small wobbly button on the neck right up against the eGo/510 connector but are placed at the top end of the battery tube still close with the shorter neck but a lower wider button to make life easier!
We figured the shoulder was intentional a year ago when that was first seen out to prevent misfiring while carrying it around in purse or pocket. One thing besides being a longer thinner battery over box mod the V3 and V4 offer in addition to usb passthrough use while charging is the lock of settings feature to prevent a bump from moving either volts or watts up or down. That's a definite plus over any Vamo for sure when I cooked one clearomizer when going to the first Vamo V2 one day and it was at 15w! not 3w where it was left set out of habit.
The SMOK Groove II
is the second box mod I went for back in January of this year as well when spotting that one with the 3800mah sealed battery by Smoktech. The button for that is a wider button but still a bit wobbly sitting on top while the main body is curved not a straight up and down rectangular shape for comfort when going to hold the larger mod there. 510 threaded however with need for adapter over the 510/eGo connector on the MVP and VTR mods for example.
The quality suffers sadly with a plastic casing and not so durable chip inside it seems. Had that until June when it suddenly went DOA when going to use it nightly! Now marked down about $20 and I wonder why? Not the best from Smoktech there by any means! I may now be grabbing a second iStick in black instead of blue since those are much smaller and can have each set up with a different flavor in even a different type of tank. I can fit two of those in a pocket I would put just one MVP but lack on the separate v and w settings.