The GSO 0.5x focal reducer provides a nominal reduction of 0.5 times and could screws on to any 1.25" eyepiece barrel. The actual focal length reduction will vary a little over or under 0.5x depending on where the focal reducer is placed exactly in the optical path.
The reducer features 2-element fully multi-coated optical design and blacked lens edges in a black anodize aluminum filter cell. It also has additional 1.25" filter threads, so you can screw/stack additional filters on to this reducer.
Included with the reducer is a 25mm extension tube.