This is an all stainless steel rod holder, flush mounted in the gunwale, with a plastic insert. A stop pin prevents rod handles from sliding all the way through.

Model RH-0D: Angle 90 Degrees; Height 8"; Diameter 2"; Flange Diameter 3.5" x 4.25" (White plastic insert)
Model RH-30D: Angle 30 Degrees; Height 8"; Diameter 2"; Flange Diameter 3.5" x 4.25" (White plastic insert)
Model RH-15D: Angle 15 Degrees; Height 8"; Diameter 2"; Flange Diameter 3.5" x 4.25" (Black plastic insert)