Product Information:Full Metal 5X Barlow Lens Barlow 1.25 inches (31.7mm) Brand: NaStarMaterial: metal + optical glass lenses Color: Black Fits any scope and lenses that takes standard size lenses. (Standard lenses are 1.25 "diameter) Very easy to use its as easy as changing an eyepiece. You simply fit this lens between the scope and your choice of eyepiece to increase the magnifcation.