I took a picture of the 11'' coil and 17'' coil for the CTX side by side. You can see huge difference in size between these. The CZ21 coil is 10.5'' and the Excal is 10''...so both are even smaller than the 11'' CTX coil. When you consider how much area you are covering sometimes it is preferable to have more/less. In my case, I usually want more as I usually hunt the dry and wet sand. As a result (*please note these numbers are far from exact as I did NOT measure exact area...they are just fun guestimates), I get about 36% more coverage with the 17'' vs 11'' coil. That is 39% more than the CZ21 and 42% more than the excal. When you start to think about that it starts to add up fast. Then if I want to go in the water I will switch back the 11'' or go to my cz/excal because in the water the smaller coils are easier to swing and control.