Parker hale Roll off mounts are listed in there catalogue No 86 as follows..
Model Rahs3(1 inch tube dia) high(.486 under tube)19 mm dovetail.
Interesting, I thought they'd be higher then that. I couldn't find a source for the rings so I made them myself, except I have .750" under the scope tube to the top of the base. .486" is more like Medium Rings.