Still sealed in bag, not sold by most Internet vendors. ONLY fits scts = or > 10".
A must for sct-owners, even if your current diagonal screws on. Used for an eyepiece for straight-through for collimation, or for photographic equipment, or for inserting any of the various 2" diagonal designs that do not come with a ring to screw on to the ota.
Standard 2" visual backs run $30+shipping (see scopestuff) screw on to some threads that in turn are on a large ring that screws directly onto threads on the tube's back. Only l0", 11", 12" and 14" scts have this ring. If you rotate eyepieces as the angle of observing changes, you have an additional ring that can rotate and potentially drop your expensive 2" eyepieces--the rotation points are
1. the large 3.25" diameter ring on the end of the tube; 2. Your 2" visual back; 3. Possibly the *barrel* of your 2" digaonal rotating relative to the rest of the diagonal assembly and 4. the diagonal tube stays put relative to the diagaonal assembly but turns inside the visual back, which on the cheap $30 version, has only one screw.
This massive visual back eliminates two of the four sources of rotation, by: 1. replacing the 3.25" diameter ring with a single unit; and 2. by having TWO, not one, brass screws to hold what you put inside it, doubling its grip.
The drawtube is solid 1/4" thick black Japanese machined aluminum. It can hold photographic equipment. Also, if you collimate with a mirror diagonal instead of straight through, it will give a more rigid precise hold in all rotational positions.
I am selling it at the *same price* as the cheaper $30 2" visual backs previously described. By comparison the top of the line astrophysics 3.25"/2" sct visual back goes for $60. So I estimate the new value of this still-in-sealed-plastic-bag equipment at $45, half way between the cheap visual backs and the top of the line competitor.
At $30 including US shipping (con US, via USPS) it is a good deal.