if you have 2 different size necks, get a hose the larger size to suit the routing and a reducer fitting[s] to fit in one end to step it down, and don't let some counter jockey tell you there is no such animal, I've had to use them on a project
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics