GUJARAT GAS Improving outlook on volumes

Just started analyzing Gujarat State Petronet as it looks attractive valuation-wise.

While studying Annual report of the same, had a basic question :- The report mentions Consolidated revenue break-up as : -

  1. Revenue from gas transportation
  2. Sale of products

Can someone explain what is this sale of products here ? If its revenue from Natural gas, then what is the difference between Gas transportation revenue and this other product