The Zero G hose is not a "flat" hose, nor, is it to be confused with the expanding hoses. A Zero G hose that is 25' long is just that, 25' long. They do "plump" a bit in diameter, but, they don't get longer. They also work just fine coiled up. I am currently using a 25' Zero G with 4' going up into the wet bay and about 7' going to my water softener, the other 14' of hose is coiled about 12 inches in diameter and it is laying in stone and Arizona Sun. It has been out there for going on 7 months this season and this is the third season it has been used this way.
I have owned those expanding hose disasters and, trust me, the Zero G is not related to those, even faintly. It is incredibly lightweight, extremely supple, and super easy to handle when cold. I had one finally start to leak. Bought another to replace it. I carry 4 25' hoses and they take up less space than a 50' white hose. Won't leave home without them.
My 2 cents, your mileage may vary...
Don
Bronwyn
Down to 1 kitty...J-Lo, the princess
2014 Thor Tuscany 40RX
2015 Jeep Cherokee TrailHawk Towed