A susceptor includes a first body including a plurality of first holes and a second body including a plurality of second holes. According to one arrangement, the second body is spaced from the first body to form a gap which allows a gas to pass from the second holes to the first holes. According to this or another arrangement, the first body is removably or rotatably coupled to the second body, or both. Rotation of the second body by a first amount or in a first direction brings at least one first hole in alignment with at least one second hole. And, rotation of the second body by a second amount or in a second direction causes a misalignment to occur between these holes.