The Explore Scientific focus extenders are special barlow lenses: first and foremost, they extend the focus of the telescope, but in a different way than barlow lenses. Thanks to its complex lens replacement system, the image is not vignetted even with long-focus eyepieces, and the pupil distance of the eyepieces is maintained. It also has an advantage when taking photos: it gives a sharper image as you move towards the edge of the field of view than conventional barlow lenses.
Excellent image sharpness and contrast, as you would expect from Explore Scientific products, and a self-contained constriction ring design.
The product box is very elegant; it features a replica of Tirion's famous star map