bulley-hewlett warmer air article

[Davy MacLean]

Just reading the bit about improving the heating system and he mentions using
A 25' box of 4" Inside Diameter R-4.3 or R-6 (if you can get it) insulated Mylar®-cased flexible household ducting. (you can get this at an HVAC specialist)

Any idea what stuff is similar an available in DIY shops in the UK?
Has anyone tried this with the above stuff or other material and how was the result
link to article

[Davy MacLean]

Bump