What they say: The Isoler thermal headband fits perfectly under your helmet to keep your ears toasty warm.
What we say: This is by far the thinnest headband on test and also the only one here with laser-cut perforations at the ear to assist with hearing. As such, we had real concerns about its insulating abilities, particularly when it came to keeping our ears warm, but these proved to be largely unfounded.
A pair of elasticated hem spins this firmly to your skull, trapping a layer of warmth in between your scalp and the fleece-backed Lycra used in its construction. Its thinness also means this fits incredibly well under your helmet, with zero need for any strap adjustment, while flatlock stitching throughout prevents any chafing. It even features a couple of dabs of reflectivity for added visibility and comes with a limited lifetime warranty.
Perhaps not one for subzero rides, but still top value. Not so much the budget option as the bargain one.