[QUOTE=Brian Bosley;6501844]In the novarossi world yes, H means cold.

Picco although Italian, TH means the short bodied hot plug. www.nitrohouse.com is a great place to get picco plugs and they show the package, the 6tc says cold on it.

QUOTE]

In Novarossi world, it goes like this
Example: The Novarossi C6TG (F) or (C)
 Product: C (Conical)
 Wire Thickness: 6
 Plug Type: T (Turbo)
 Plated: G (Gold plated)
 Thermal Range: F (Fredda = Cold) C (Calda = Hot)

The plugs with cold thermal range F (Fredda), have a body with thinner walls and shorter body, so they dissipate heat better and faster to the engine head.
The plugs with hot thermal range C (Calda), have a body with thicker walls and longer body, so they retain heat and dissipate heat slower to the engine head.

AFM