TSR 1 Inch Low (.785) The most precision scope rings on the planet Ring bore diameter circularity (roundness) within 2/10000 of a thousand's Ring bore parallelism and perpendicularity to ring base less than 1/10000 of a thousand's Direct supplier to Canadian defense ministry for the c14 timber wolf .338 lapua (mrsws) Manufactured in the United States by US Veterans from 7075-t651 aluminum alloy