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Castelli Thermoflex Arm Warmer

Nothing beats a great arm warmer when your ride gets cool and wet. Except perhaps a tangible upgrade. Long a favorite style of warmer wearers everywhere, the Castelli Thermoflex series has been lauded for it's comfort and protection. With the Thermoflex+ series, the Italian company has improved the already good fit and freedom of movement without sacrificing the protection level. Thermoflex+ Armwarmers are perfect for rides or segments of rides that take place in the mid-40's to mid-60's Fahrenheit when cool air and/or precipitation are in play.

The proven Castelli Nano Flex system takes a soft, stretchy, lightweight, breathable, insulating fleece fabric and treats it with coating featuring millions of nanofilaments. The resulting finish repels water completely, instantly beading it up and shedding it. Well proven in warmers, bibs, tights, and other pieces where garment flexibility and protection are desired, Nano Flex blocks wind and repels water with ease.

The big addition to the Thermoflex+ Armwarmer is the addition of a back side panel of the lighter, even more flexible and comfortable Nano Light material, which has less insulation, but the same water repellent capability. Out of the wind, behind the arm you don't need more insulation, what you want is complete freedom of movement, zero bulk, and great fit without too much tension. Nano Light gets the job done and makes the Thermoflex+ a true upgrade on an already fantastic warmer.

Fit and finish are fully anatomic, allowing you to forget you are augmenting your clothing with a warmer. Castelli employs a double silicone gripper system - inside and outside the arm warmer so the piece will hold in place on the skin, as well as under your short sleeve jersey, Gabba of Perfetto Light protection pieces, for maximum retention no matter how hard you go, no matter how wet it gets.


  • Upgraded Excel Staff favorite arm warmer for cool, wet rides
  • High stretch and moderate compression with this light thermal warmer
  • Breathable, yet blocks wind and repels water with ease
  • Nano Flex base fleece layer with nanofilament treatment for protection
  • Nano Light insert on back of arm for extra stretch, bringing better fit and comfort
  • Double-sided silicone grippers to keep the warmers in place
  • Less overall bulk makes the Thermoflex+ wamers even more packable
  • Ideal for temperatures from 46-65°F, especially when wet
  • Sizes: Small, Medium, Large, XL
  • Color: Black
  • Weight: 69 grams (Medium)
Sale Price
Reg Price $39.99
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Castelli Sizing Chart

Mens Shorts, Bibs, Knickers & Tights
Mens Jerseys, Jackets & Vests
Womens Shorts, Bibs, Knickers & Tights
Womens Jerseys, Jackets & Vests
Palm Circumference6-7"7-8"8-9"9-10"
Mens Socks
Womens Socks