Freedom Flex Venting by Wolf Steel 

This video is excellent. Shows benefits of the flex system and obstacles of solid systems. Fascinating how they make it too! Only one thing I don’t know. Where to get the invisible caulking... Hahahaha....

Is this venting option limited to gas fireplace brands? Or is it an option for all brands of fireplaces?

What is the proper clearance for this type of venting? Looking in manuals it does not mention any clearance for this flex vent system.

Single wall liners are not to Code nor meet NFPA code 211