Mr. Funnel is also sold under the RACOR brand name.
I am a Mr Funnel dealer in the Keweenaw. One customer who came many miles to get one told me he blew up his very expensive modified sled last winter when sucked water into the engine. They work well at keeping water out of the fuel, very critical if you are a boater or fly a small airplane. One hiccup could mean the end. If you fill from storage cans, moisture contamination is very likely and of the fuel has ethanol, even worse with moisture.
I know people who use them when they fill generators too.