A high quality 1.25" barlow lens made entirely of metal. Fully multi-coated (FMC) doublet achromatic lens, results in high resolution and contrast.
Barlow lenses are used to multiply the focal length of the objective lens/mirror of your telescope and therefore it's magnifying power. The benefits of using a Barlow lens will result in image magnification, improved eye relief and reduced spherical aberration in the eyepiece.
The Opticstar x2 achromatic barlow can be used for both observation and imaging. For imaging purposes it will increase the focal length of say a 200mm f4.8 Newtonian reflector from 1000mm to 2000mm thus increasing the surface area of say Jupiter by a factor of 4 (i.e. a x2 increase on each axis).