Kim, i am currently using the small blue tinted silicone tubing in my small 2 or 3 oz. tanks. In the bigger tanks the normal size will work fine.  I believe it is Dubro. I have tried neoprene, small latex and surgical tubing and they have all either split or bent forward in the tank upon landing. The tubing seems to flex and work better than you would think, not having to slide all the way to the extreme sides, tops and bottoms to pick up fuel. The small tubing is somewhat hard to get onto the fittings, but i find if i take my time it will work.