I had 4 Rocket Man servers when I ran my roasting business. We used them at the local university for home football games, delivering coffee in the stands. We also used them at events downtown. I obtained a permit to walk the sidewalks and sell or give out samples. During our tree lighting ceremony around the square we went out with a few backpacks full and gave out 4 oz samples of our coffee. We drained all the packs within 20 minutes. everyone thought they were the coolest things they ever saw.
They worked very well. They hold about 2.5 gallons. The canister is very much like a "Cornie" or a "Sixer," if you are familiar with beer brewing/kegging. You use a pump similar to a tire pump to pressurize the tank. Before you serve, you need to bleed off a little air so it does not sputter. Same is true when you get toward the end of the container; don't try to serve it when it sputters...you will end up getting it on yourself or a customer. I never had a problem with it cooling down too much before I had it all served. They are fairly heavy, but have a good waist harness that helps support the weight. Our guys wore aprons that held lids, sweetener, creamer packs, etc.
Shep