Refillable 510 Cartomizers 2.0ohm
I use the above Boge style or kr808's when I am not dripping
I started using them for the same reason you are describing...needed something that I knew would last me for a few hours at least or that I could be on the road with and not dripping constantly. The ones linked are very easy to refill, you just take off the end cap and fill into the white filler material...it adds about a quarter of inch to the length of the unit as they are slightly longer than a cart/atty...well no thats not entirely true. I Use a drip tip on the end of my cartomizers and that's what adds to the length...and while I recommend that so you can refill them even faster its not needed. The ones linked hold .8ml but seem to be more efficient as using the liquid than carts.
I have every type of cartomizer that I have seen, from the r4's to the joye xl and I just find the simplicity of filling the boge ones are worth the lower juice content...once you pop the top off you see...
a white filler wrapped around the central heating element...you just drip your juice into the filler material and it lasts however long a .8 ml normally last you, I have never had one leak, if its for work I normally bring a bottle of juice or an extra just in case it runs low. A boge cartomizer normally lasts me 4-5 times longer than a standard 510 cart...and the taste is more consistent as well, the downside is that they are disposable....but that may be an upside as well...they last me about a week so a pack lasts me a month, the trick is to make sure they never completely dry out, but if one stops performing well its not big deal to toss it and get another.
I still use my atty/drip tips for testing new juices...or just goofing around the house...but for on the run a cartomizer is a hard option to beat unless your getting a full bottom feeder mod (the ones with the juice bottle attached)