18 x 12 Standard Trim Plane Assembly. Bennett trim planes are made of high-quality 304 stainless steel and remain strong and rigid, even in the most challenging situations. Each trim plane assembly includes a trim plane, backing plate and hinge for one side of the boat.WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.