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Castelli Pro Seamless 2 Arm Warmer
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Castelli Pro Seamless 2 Arm Warmer

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Mfg PartNum:
rating(5 customer reviews)
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MSRP: $29.99
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A Better Arm Warmer

Castelli saw room for improvement in typical warmers on the market, so they set out to make an arm warmer unlike any other. The Pro Seamless 2 Arm Warmer suits a wide temperature range for comfort on any ride.

Typical warmers on the market are made with a nylon and Lycra® blend that tends to hold moisture, but Castelli knew they could get better moisture management with polyester yarn. Working with polyester makes it more difficult to get the right stretch, return, and manufacturing consistency, but in the end, it's all worth it. This mid-weight warmer is great even when not worn since they fold up so small, and the fully seamless construction eliminates itching and chafing.

The Pro Seamless 2 warmers are a pro rider favorite because they're crazy light and they're extremely warm for their weight, yet even in milder conditions, you don't overheat.


  • Mid-weight seamless arm warmer
  • Surprisingly warm without causing overheating
  • Unique polyester/nylon/Lycra® blend
  • Fully seamless construction
  • Folds up extra small

B-Stock - This product has one or more B-Stock units available. These units can be purchased at a discount (see option select). B-Stock units were returned from other customers and may have missing or damaged packaging materials. These units are otherwise as new. The full manufacturer warranty applies. Click Here for more information.

Size Chart



Black - S/M

Mfg PartNum: P4521541010-2 

Black - L/XL

Mfg PartNum: P4521541010-4 


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5 stars
4 stars
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1 stars
Excellent mid-temperature arm warmers
by loneoceans
Cycling Enthusiast
Seattle. WA
2 of 3 customers found this review helpful.

Over the years I have used Pearl Izumi pro thermal arm warmers. Those are great but I always wanted something that was a touch less warm and more breathable. I found the perfect pair of arm warmers in the Castelli Pro seamless 2. They provide just enough warmth for nippy fall days, but are much more breathable than my pearl izumi ones for hard intervals. Also, I thought that it couldn't get more comfortable than the pearl izumi ones, but these are even more comfortable, and they are very well constructed with a very engineered fit. Highly recommended.

Reviewed 1/13/2022
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Arm sleeves vs. Suncreen
by Bruce
1 of 2 customers found this review helpful.

I never ride in the sunny and warm season anymore without wearing arm sleeves. It's the best "sunscreen" application there is.

Reviewed 1/14/2022
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by Anonymous
Southern Oregon
3 of 3 customers found this review helpful.

These arm warmers are exactly what I wanted. They're light and roll up small, yet they're surprisingly warm. I have some other-brand arm warmers that work well, but they are stiffer, heavier, and not much warmer. They have seams, so you need to get them on just so. The wrinkle a bit in the inside elbow, so they aren't as comfortable.

A nice thing about these sock-like warmers is that you can just roll them down to the wrists for the climbs and back up for shady descents. No need to take them all the way on and off over gloves.

Also, these stay smooth and don't wrinkle or bunch up, so they stay aero.

They stay up just fine, but I use a trick: smear a light layer of Vaseline on arms/legs where you want the warmers to stay up, and they won't slip down. These warmers stay up pretty well on dry skin, but I always use my trick before riding for 100% reliability. I hate when warmers slip during rides!

These are really perfect for cool and variable conditions. And they do surprisingly well down to the high 40s (~9C).

Reviewed 11/25/2022
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Favorite arm warmers.
by Michigan biker
Competitive Racer
SE Michigan
1 of 1 customers found this review helpful.

Castelli nailed it with these seamless leg, knee and arm warmers. They must use a very high loft insulating fiber to knit them. They are super soft, stretchy and very warm for their weight and thickness. Although they look small when you get them, they stretch a lot. And thus far have not lost their shape or rolled down.

Reviewed 5/12/2022
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Warm and comfortable
by Anonymous
Cycling Enthusiast
Plano, TX
1 of 1 customers found this review helpful.

Surprisingly warm and very comfortable. These are short for me (I wear 36-37 in. dress shirt sleeves) -- even shorter than other arm warmers that I wear -- but I still like them when a need something mid/light weight for 50-60 (F) temps

Reviewed 12/30/2021
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