Replacement O-ring for Thompson Valve II Abrasive Metering Valve Spring Retainer. BlastOne Thompson valves are one of the most popular abrasive grit valves on the market. Many years of infield use have proven them to be durable and reliable. BlastOne is a global blasting equipment and consumables supplier. See us for a full range of abrasive blasting equipment, abrasive blasting media and industrial coating equipment.