O & K American Corp.
O & R Precision Grinding
O & S Research, Inc.
O/I Analytical Corp.
Oakwell Inc
Oberg Industries Inc
OBERG INDUSTRIES INC.
Obus Forme Ltd.
Ocean Products Research Inc.
Off Site Manufacturing Inc
OFI Testing Equipment Inc
OFS Fitel, LLC
Ohio National Guard
Ohio Precious Metals
Ohio Valley Aluminum Co
Oil City Iron Works
Okabe Co Inc
Old Federal Tool Company Inc
Old World Industries
OMC Precision Products
Omni Corporation
Omni-Circuits, Inc.
Omnii Oral Pharmaceuticals
Omni-Tech Corporation
OneSource Building Technologies
On-Hand Adhesives, Inc.
Onicon
Ontario Fluid Power
Ontario Process Control Services LTD.
Onward Coatings Co LLC
OPEN SYSTEMS INTERNATIONAL
Optel-Matic Inc.
Optimum Power Technology
Optinova
Opto Diode Corporation
Optometrics USA Inc
OPW Engineered Systems
Orangic Dyes & Pigments
ORC Industries/Lacrosse, WI
ORC Plastics/Charlotte, NC
ORC Plastics/Siler City, NC
Orcon Corporation
Oregon Rubber Mills Co
Oregon Scientific
Orotex
Orthman Manufacturing Inc.
OSA, Inc.
Osborn Scientific
Osterneck Company
Ostrem Tool Company
O'Tech Corporation
OTSCON Inc.
Otto Industries
Outbound Technologies, Inc.
Ovidon Manufacturing LLC
Owens Corning
Owens Corning Automotive
Oxford Tool & Template, Inc.