Aimtech only recommends this for a Benelli M-1 Super 90, 12 gauge.
It fits my 1201FP with rifle sights perfectly, but I'm not sure if wouldn't fit the ghost ring sight model. Only took a bicycle spoke to hand-push out the trigger group pin and this slid right on. The only issue I encountered was the groove in the mount for where the bolt cycles back wasn't wide enough for my aftermarket oversized bolt charging handle and I'll have to go to a smaller bolt handle like it had originally and they just snap in. An added bonus is there is just enough of a gap under the rail to use the rifle sights as backup if needed.