This Propane Fitting is for connecting HIGH PRESSURE Flow Quick- Disconnect 1/4" Male Plug to make it as an adapter to allow gas to flow to brass fitting and lines. 

If you want to go on to low pressure systems, like a Y adapter or line fittings ... READ BELOW.

Some RV hook up on lines might be all HIGH-PRESSURE GAS & LINES and / or have NO PRESSURE REGULATOR.

Use of this adapter fitting is to the High-Pressure fittings and lines to make this connection as long as it is having a LP PRESSURE REGULATOR on the system before the grill or appliance. Fail to follow this will cause full amount of fuel to flow and fire or explosion!

How you can tell what this adapter is to your items that will not let gas flow but connects to the disconnect socket (See in photos).

Item for sale is the one on the LEFT (High Pressure), compared to the one that stops me from getting gas flow is on RIGHT (Low Pressure).

LEFT: 

1) Same size hole on outside.

2) Smaller size hole on inside.

3) Machined larger thru hole (from looking down threaded side).

4) This fitting (and most socket connectors) has letters & numbers to code what it does or what it will fit, 5LP, 5LP-A, 5LPN, (this one      is 5LP-A-6 MBS). Has the area that is narrower on the band to lock in on the socket.

RIGHT:

1) Same size hole on outside.

2)Larger size hole on inside.

3) Machined smaller thru hole (from looking down threaded side).

4) Low Pressure Fittings will have NO markings, 250, low pressure or on the socket. The area on the band is wider on low pressure        fittings.

Some say they got adapters or lines that connect but no flow of gas, switch over to this will allow that flow and use the items!