Centrocerin lubricant is recommended (but not required) for all Innoflue SW (Single Wall), Flex & Concentric connections (pipe to pipe, pipe to fitting, pipe to adapters, etc.). A dime size amount is sufficient for an average 3" or 4" connection (less is needed for 2"). A single 50ml tube is generally sufficient for about 20-40 connections depending on pipe size and amount of connections (2" - 5") - adequate for a typical residential roof, chimney or through-the-wall installation. See page 5 of the Installation Manual for details.