Tele Vue's barlow lenses are individually tested to perform with f/4.0 telescopes without degradation anywhere in the field. Both optical elements within the barlow are fully multicoated, and it accepts 48mm filters.
Offered exclusively in a 2x magnification, the 2.00" barlow is great for Newtonian telescopes and will be parfocal with both 2.00" & 1.25" eyepieces.