This 2" 2x Clamp Ring Big Barlow can be used with any telescope using a 2" focuser. As it is only 4.5" long, it can also be used
in most 2" star diagonals for 2x magnification.
It can also be placed into a 2" focuser in front of a 2" star diagonal to give higher magnification than the nominal 2x. Some refractors might not have enough focuser travel to allow this directly, however. . . .