Please note: This text was taken directly from the manufacturer.
Give your scope a power boost! Orion's Shorty barlow lens doubles the power of any eyepiece it's used with. For about the price of a single telescope eyepiece or less, this practical accessory effectively doubles the number of eyepieces at your disposal. It gets its name from its compact size. The Shorty barlow lens is just 3" long end to end - about half the length of a standard barlow lens. It's short 1.25"-diameter barrel is just 1.6" long, fitting easily in any 1.25" star diagonal, so it's great to use with refractors and Schmidt-Cassegrain telescopes. In fact, it works with any type of telescope. The Shorty's 2x amplifier lens is an achromatic glass doublet that's multi-coated to ensure excellent light transmission. The machined and anodized aluminum housing is internally baffled to eliminate unwanted reflections and increase contrast. Barrel is threaded to accept filters.