The poly venting octagon jamb extension kit is designed to be applied to the interior jamb extending the depth from 4-11/16" up to 6-11/16". The kit contains 8 pieces clear Pine measuring 11/16" thick x 2" deep and is mitered on both ends to match the size of the octagon window. Also included are 8 stainless steel clamp nails for solid assembly prior to attaching to the window. The wood parts of the kit are shipped unassembled so they can be trimmed to match your exact wall thickness.