The Workforce Heat Holders® massive 4.7 Tog Hi-Vis Hat is exceptionally thermally effective, with a HeatWeaver® plush insulating liner specially developed to hold heat in.

The soft fur-like lining feels great against the skin (this is one time it almost pays to be bald!) and it's also very efficient at using the heat that naturally rises from your head to keep you warmer for longer.
 
And the special reflective strips mean you're sure to be noticed!

Outer: 53% Polyester 47% Acrylic, Lining: 100% Polyester
1 Pack
HeatWeaver® plush lining
Stretchable rib construction
Advanced insulating yarn
Machine washable at 40°