Depends on how much you want to spend, I got a perrin one from scooby clinic, ptp are another well respected brand but you'll have to ship from the states,
I have mine without the heat shield, the ic is cool to touch after a long run and can also put my hand on the blanket,
Some of the UK sellers blankets are 2x as much and I can't see why,
Cdf, do them amongst others