Ended up using this 12" one ( https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 ). fit's just fine. I suppose a guy could probably jam a 13-14" one in there but even this 12" one makes the text PLENTY big. Already has the twist lock BNC connector so no adapters or anything like that needed and I bet the connector is also the reason this monitor shows the text rock solid and sharp instead of the issues other folks have been having with less than perfect images. Probably the adapters? I also went ahead and ordered a $25 50W LED light (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1) and replaced that old spotlight in there. The whole thing is crazy bright now. (almost too bright). My next step is figuring out why my Beacon light isn't working (by the way if anyone knows what i could check or if there's a fuse or relay for it I'd really appreciate the info). I want to put in a new one with a buzzer on it so i can hear when the machine finishes it's cycle.