This is the great Williams Diagonal for refractors. It's in "like-new" condition and is just 6 months old.
It has a precision 1/10 lambda surface with 10mm mirror thickness. It includes the 2"- 1.25" adapter with copper clamping ring. Inside diameter (48mm) includes the capability to connect variety of filters.
These now sell for $130 from Williams, I'm selling mine for just $99 shipped in CONUS.