This Ultima Barlow lens is without doubt the #1 choice among amateur astronomers who want the best performance from their optics. The Ultima Series 2x Barlow (31.7mm [1¼"]) is an air-spaced, 3-element apochromatic design with a 27mm clear aperture. This lens features a very high quality, fully multicoated design. Amazingly compact and lightweight, it’s just 142grams and 69.85mm in length.
A 2x Barlow lens doubles the magnifying power of your eyepiece by doubling its effective focal length.