The refractive properties of Flouro' mean it does almost disappear underwater, and its density nails it down to the lake bed to avoid spooking fish. All this combined with minimal stretch for improved indication mean that X-Line can truly give you an edge. Just take a look at the Korda DVD series to see just how well it works.

One thing to be aware of is that fluorocarbon by nature is stiffer than mono, so if your looking to cast any reasonable distance stick to a 12lb or 15lb line. Above that the springiness' can make things go a little pear shaped but if your after a line specifically for margin work the 20lb is still well worth considering for their extra strength and weight gives great confidence and sinks hard. 

ts quality gear though and well worth a look.......not that you'll see it!