12-20-2011 Oklahoma Approves Pro-Ring Manhole Adjustment System
The State of Oklahoma Department of Transportation has reviewed and condititionally approved the use of the Pro-Ring Manhole Adjustment System for use.
See the attached PDF for the Letter of Approval
02-01-2012 Pro-Ring added to St. Loius. MSD approved materials list.
The Metropolitan St. Louis Sewer District has approved and added the Pro-Ring Manhole Adjustment System to their approved material list.
Please click on the official St. Louis MSD engineering weblink for more information about the approval.
http://www.stlmsd.com/engineering/general/approvedmaterials/manhole-adjustment