This is an all aluminum adapter to allow the use of 2" accessories in a Unitron focuser. It is made from a solid block of aluminum and has three radial set screws to hold your accessories. It threads directly into the large 2.4" Unitron draw tube. It is 3" in diameter and extends 3/4" outside the draw tube. I can send some more e-pix if you want. $65 shipped in the U.S.