This is a 2" - 1.25" adaptor with twist lock for centering eyepieces and collimators for precise set up. Very high build quality and easy to use. The top silver ring completely unscrews to reveal T Thread turning it into a 2" - T Thread adaptor also.
If you have a William Optics refractor 2" SCT diagonal (or clones), you can now purchase this simple adapter to turn it into a push-in diagonal, simply remove the 2" SCT ring and replace with this nosepiece.
This is a great adaptor that screws onto the back of a standard SCT and provides a 2" female with twist lock. This allows you to use 2" accessories such as camera adaptors and also diagonals with your SCT visual back.