Other Mounts Williams 1" H.C.O. Rings. PreviousWilliams 1" Split Rings NextWilliams Interchangeable Split Rings with Extension. 26mm. Williams 1" H.C.O. Rings. Williams 1" H.C.O. Rings. from $79.00 High central overbore rings, compatible with Williams Quick Convertible Side Mount. Height/Grade: Select Height/Grade 1" New Old Stock or Restored1" Used 1" New Old Stock or Restored 1" Used Quantity: Add To Cart Facebook0 Twitter