don't know about this one, but the thing looks like the old bigfoot coil
i have a 14" excelerator coil for my m-6 not that impressed, good for field hunting
must turn down senitivity to about half. it good on telling whats in the ground
pinpointing depth is not correct, i heard that my machine is calibrated for the 9.5 coil
and thats why you must fiddle with the knobs with the larger coil.
if you hunt in tall weeds, thickets or trashy areas, it ain't easy with those bigger heads.
in this case bigger is not better in my opinion. stick with what you got.