Twist-lock barlows make for easy eyepiece in-out and work with any barrel format. These extend focal length, reduce spherical aberration, extend eye relief, and have the T2 camera thread with the Twist-lock collar removed. The 1.25"UB2STL is a fully multicoated achromat with a 27mm aperture and increases the focal length (and eyepiece magnification) by 2 times.