Push Button Gas Door

[glider.]

"Steve07" posted this as a replacement for the barrel key on the bagger fuel doors that all keys fit regardless of the bike.

HD part #53909-04A...$22.36 at Zanotti's.

 

[Breeze3at]

I just found out that part # 53842-00C is a lockable push button. About $30.

 

[biglew55]

There are two versions. Here is the other one:
Genuine Motor Accessories | Harley-Davidson USA
Kuryakyn also has a version of the 'Smooth' one, but the HD one has worked great for me.