The 2.5x Luminos 2" Barlow Lens from Celestron extends the effective focal length of an optical tube by 2.5x. This telescope accessory features a fully multicoated optical path with four lens elements designed to improve color fidelity and transmit a field of view that is flat from center to edge. The eyepiece holder is threaded to accept 2" eyepiece filters and will accommodate 1.25" and 2" eyepieces; brass compression rings secure the eyepiece without damaging the barrel's finish. The aluminum housing is finished with an anodized hard coat for enhanced scratch and corrosion resistance.