Don't go with the Koplin packs that are sold in the local stores. If you search around online you will see a number of reviews that note they tend to leak.
Rotopax used to make Koplin's product line years back until Koplin decided to switch the design. However, along with Koplin's design change came the leakage issues that have been noted on many of the atv forums.
Rotopax on the other hand have great reviews by all the ATV guys that use these. I ended up purchasing 4 of the gas fuel packs from Rotopax. The fit perfectly on top of my GOBI roof rack and are low profile enough that they don't cause any wind resistance.
I filled them up when I left Houston and drove all the way to Cloudcroft, NM with them. I had forgot to leave some space in the fuel packs for expansion due to elevation and being out in the sun. Needless to say when we were on top of one of the mountains I hoped up to take a look at them and they expanded more than I could believe. I thought for sure that there had to be leaks, but upon closer inspection there weren't any issues at all.
Get two thumbs up in my book and are a nice alternative to jerry cans.
