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CastelliNano Flex 3G Arm Warmer


Item # CST00UJ

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Item # CST00UJ

Nano Flex 3G Arm Warmer

Rain or shine, wet or dry, these warmers give you the extra bit of warmth you need to stay comfortable when you're riding on a brisk day in early fall or late spring. The stretchy, fleece-backed thermal fabric is coated with millions of tiny nanofilaments that encourage water to bead up and roll off the garment, keeping light rain and tire spray at bay. That being said, the material is also highly breathable, making them a great option for dry days, too.

  • Arm warmers that work well for both wet and dry conditions
  • Water-repellent thermal fabric helps you stay warm and dry
  • Breathable construction prevents clamminess and overheating
  • Single, flat-lock seam ensures maximum comfort
  • Double-sided silicone gripper keeps the warmers in place
  • Easy to take off and stow in a jersey pocket if things warm up
  • Recommended for temperatures ranging from 54 - 68-degrees Fahrenheit

Tech Specs
MaterialNano Flex 3G
Recommended Useroad cycling
Manufacturer Warranty1 year


Arm & Knee Warmers





Rider Weight

99.2 - 132.3lb

(45 - 60kg)

99.2 - 132.3lb

(45 - 60kg)

132.3 - 154.3lb

(60 - 70kg)

154.3 - 176.4lb

(70 - 80kg)



Short/Jersey Size XS - S S - M S - M L - XL 2XL - 3XL
Short/Jersey Size:
Take your typical cycling short or bib sizing for comparison.

What do you think about this product?


>Rating: 5

Excellent Warmers

I've used it several times
Runs small
Size Bought
5` 10"
180 lbs

They feel premium and do a great job at keeping my arms warm. As always with Castelli be sure to size up. Worth every penny

>Rating: 1

Poor Customer Service

For two weeks I've been trying to resolve a simple warranty issue. I bought Castelli arm warmers and within the year warranty period they ripped at the silicone gripper. I sent photos to them. Backcountry would only replace if I cut them up. I was attempting to wear them as they are the only pair I have. I offered to cut them up once the replacements arrived. They wanted no part of that. The arm warmers are defective whether or not I cut them up. To insist on cutting them up before they will ship new ones is taking advantage of me and my ability to continue to ride my bike. Very poor customer service.

Thanks for posting. They could just charge you for new ones and refund you once you cut up the old ones. Such a silly way to get a bad rep.