Not sure if you understand that coils can be made for any detector by any aftermarket company just like aftermarket rechargeable batteries, covers of all makes and sizes, stands, ID meters, etc. The MGC coils are not pirated but are made to work with other units just like any aftermarket coil company - NEL, Sun Ray, Cors, etc. They just so happen to make a few for the X Terras. Wonder why? Could it be that the X Terras weren't worth a flip when operated with the standard concentric stock Minelab super duper engineered coils in any frequency? Why was the 18.75 DD coil the coil everybody wanted? And the clever "change the frequency with the coil" concept. Why didn't they didn't they just stay with one or 2 coil sizes and change the frequency in the detector programming? Maybe they had a marketing genius that said when they buy the X Terra, the poor guy that bought it will have twice his $ wrapped up in coils. Well, then comes along the MGC coil company that makes several aftermarket coils for for the Fisher F75, AT Pro, X Terra, Garrett Ace and a few others. I don't think it's all that hard to take anything apart and duplicate or even make it better. The Japanese have done that to the US since WW2 on just about everything you are using today.
I purchased one of MGC coils a week ago and have never seen a coil built like a tank, light and such a $ value. The coax cable is none like I have seen. Thicker than any but more flexible. They all come with coil cover and even a signed 2 year warranty card. My buddy is using his 5" DD on Ace 300 and is now bugging me to get him the 13" and a one for his AT Pro. I will be getting one for my F75 and Racer 2 also. Might check them out....