Giordana's FR-C seamless arm warmers aren't truly seamless – there's still a flat-locked stitch running the entire length – but they're exceptionally comfortable nonetheless and an excellent choice for riders seeking a sleek racer-type look and fit.
The thin Dryarn fabric wicks moisture well but isn't all that insulative compared to heavier-weight fleece-backed warmers. As such, think of these more for early spring rides where temperatures can start out cool and end up warm. The material still protects your skin from cold air and freezing road spray, though, while its excellent breathability extends its comfort range.
Where the 'seamless' part does come in, though, is in the differential weave throughout the warmer. The inside and outside of the elbow get different fabric densities from the rest of the piece and sections facing the oncoming air are more tightly knit, resulting in a highly elastic and truly second-skin-like feel that provides more protection than their feathery feel would suggest.
They're unnoticeable while riding and don't annoyingly creep down your arms. More petite riders will find the unisex sizing to be on the long side, however, and at £39.99 (US$60) a pair, the Giordana FR-C Seamless Arm Warmers are also pretty expensive.