Replacing the fill valve to the propane tank on my MH.

[furbspop]

I am replacing the propane filler valve on my 2012 Fleetwood Storm 28ms and am looking to purchase it on-line. I see that there is a "Fill Valve" and also a "Double Check Fill Valve". Can some tell me what the difference is? Thanks.

[Old-Biscuit]

Double Check Valve
Has same upper check valve like standard filler valve and also has a lower check valve (back pressure valve)

Upper and lower sections can be separated......upper can be removed/replaced w/o emptying tank

1 1/4" threads with 1 3/4" hose thread

[furbspop]

Thank You for the clarification!