F&G system...
[USER=3917]@rivstg1[/USER]: The F&G system is sort of a hybrid between top- and bottom-fill. The connection for the bag is at the bottom but the bags themselves have a built-in fill tube (or snorkel, as I call it) that brings the dirt into the bag at the top. This is is somewhat problematic because dirt invariably gets trapped in the snorkel. I had this happen when I changed out my Sanitaire's F&G bag Sunday. The solution Vinvac is suggesting adds an adapter, essentially an extension tube so that one can use true top fill bags. KestinFox's suggestion apparently accomplishes the same thing but with Kirby bags.
[USER=4865]@kestinfox[/USER]: Can you post pictures of your Kirby setup? I've got a spare Kirby fill tube and bag connector but the tube is round and the connector on the Sanitaire is oval. I'm not sure how to bridge that difference. Does the Kirby fill tube flex enough to fit over the F&G connector? Does the spring band hold it in place or would one need something like a zip tie or radiator hose clamp? I do hope there is a more elegant solution than duct tape.