Vixen 2X Barlow lens with 31.7mm T2 thread

This Barlow can be used conventionally for observing with a 1.25" eyepiece, but it can also be used as a SLR photo adapter.  On the observing end of the unit there's a T-threading; simply attach a Vixen T-mount (listed here as accessories) to use this Barlow together with your SLR camera