I use the model X-305 for holes up to 12" and up to 17" with the X-425 version. The shield controls the dust and acts like a portable drill press keeping the hole cutter aligned perpendicular to the work piece. The blades cut well through wood, MDF, plywood, OSB, and even fiber-cement board (when I installed some outdoor speakers in a soffit around the house.
Safe and easy to adjust for the exact size needed for the cut-out. I even used the X-305 to help a friend make holes for ceiling speakers in his house with its lathe and plaster ceilings. Perfect holes and no worries about cracking the plaster.
I got mine at
www.holepro.com