National Sales Company is also listed under the following categories: Standard Yellow Pages Heading (SYPH) Categories:

• Backflow Prevention Devices & Services
• Pipe Retail

North American Industry Classification System (NAICS) Categories:

• Plumbing, Heating, And Air-Conditioning Contractors > Septic Tanks & Systems > Backflow Prevention Service
• Plumbing And Heating Equipment And Supplies (Hydronics) Merchant Wholesalers > Septic & Cesspool Equipment > Backflow Prevention Devices & Services
• Other Building Material Dealers > Drains & Pipes > Pipe Retail

Standard Industry Classification (SIC) Categories:

• Plumbing, Heating And Air Conditioning > Septic Tanks & Systems > Backflow Prevention Service
• Plumbing And Heating Equipment And Supplies (Hydronics) > Septic & Cesspool Equipment > Backflow Prevention Devices & Services
• Lumber & Other Building Materials > Drains, Pipes & Sewage Materials > Pipe Retail