Stock Materials Rotary Natural Birch Strek-O Solid Core 1-3/4" Doors BCM Commercial carries two solid core, 1-3/4″ wood Veneer doors. Rotary Natural Birch (fire-rated optional) and Plain Sliced Red Oak veneer. From stock: 3’0″ by 6’8″ or 7’0″ doors. See Machine sheet below. Door Machine Sheet PDF Plain Sliced Red Oak