The Orion 2" Zero-Profile Prime Focus Camera Adapter couples your camera to a telescope for prime-focus astrophotography. It threads directly into the T-ring (sold separately) for your SLR/DSLR camera body.
I was having difficulty getting the CCD (DSMI II) aligned on the focus plain using the 1.5" nosepiece and the adapter on the Low-profile DS Crayford. Still need to be precise when mounting in the focuser, but my diffraction spikes are no longer fan outon one side. It did not come with a 2" cap to use when not in use.