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Pro Issue Short-Sleeve Baselayer - Men's

4 out of 5 stars
4 Reviews
Current price: $35.99 Original price: $59.99
40% off


Size Chart


Pro Issue Short-Sleeve Baselayer

The days that you feel a slight chill when you step outside are often the toughest to dress for. The sunny skies suggest you'll quickly warm up, but you don't want to spend the first several miles of your ride fighting off a chill. For rides like this, grab Castelli's Pro Issue Base Layer. This lightweight polyester crew-neck top fits under your jersey and helps facilitate moisture transfer from your skin to the surface to regulate your body temperature. It won't be as insulating as Castelli's Flanders base layers, and it won't cool you off as much as Core Mesh, but it will do a little of each to keep you comfortable on the rides that are difficult to categorize.

As far as construction, Castelli eliminated more seaming in this latest version of the Pro Issue to enhance comfort, and it widened the collar to give it a more streamlined fit under aero jerseys. The flat waist hem helps prevent chafing or irritation by laying smoothly against the skin in shorts, and according to Castelli, the base layer functions best in temperatures ranging from 59 to 77 degrees Fahrenheit.


  • Late-spring, early-fall professional base layer
  • Specifically designed mesh fabric moves moisture away from your skin
  • Upgraded seams at shoulders provide a more comfortable fit
  • Wide collar goes well with current generation aero jerseys
  • Flattering waist hem lays flat under bib shorts
  • Castelli's roots in performance cycling textiles date back to 1910
  • Item #CST008Y
polyester 3D mesh
Insulation Weight
Claimed Weight
[large] 1.7oz
Manufacturer Warranty
1 year

Overall Rating

4 based on 4 ratings

Review Summary

1 Stars - 0 reviews
2 Stars - 1 reviews
3 Stars - 0 reviews
4 Stars - 1 reviews
5 Stars - 2 reviews

Fits Small

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


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5 out of 5 stars

April 10, 2024

Great Baselayer!

I've put it through the wringer

I've been finally adding baselayers to my cycling gear and it's made a huge difference especially on those cold descents after a long climb. This is one of the gems acquired in that process. I love how light it is.

Originally reviewed on

5 out of 5 stars

November 16, 2023

Perfect for when there's a bit of chill

I've used it several times

These are great when there is a bit of a chill in the air and you know you are going to warm up fairly quickly but don't want to overdo. I am 70 years old and ride in sub-zero temps; I don't use this then unless for an under-under layer; I use these when it is not bad out but I don't want the old man to take a chill. Perfect for that and excellent quality; durable and I let them dry after the ride so no need to over wash. I'm ordering another one.

David S

Originally reviewed on

2 out of 5 stars

June 29, 2023

Run Small - For Hot Summer

I returned this product before using it

I am 5'10" and 175 lbs, and usually wear a large with Castelli clothing. These undershirts run small; I ordered a large and had to return them as they were just too tight. Also, while they appear to be very nice undershirts, they are very thin and appear to be meant to worn on the warmest riding days. I was looking for something with a bit more fabric. The description does not seem accurate to me.

Clifford S

Originally reviewed on

4 out of 5 stars

April 12, 2020

Vital piece of kit for cool days

I've put it through the wringer

This is my first cycling base layer that isn't for winter. I was skeptical prior to ordering, but have become a true believer. I just did a Century ride where the temp started at 61 degrees and warmed up to 77. Not once was I cold OR overheated. I did a fair amount of climbing and would unzip my jersey half way for the ascent and then zip it back up for the descent. Absolutely perfect for this temperature range. For sizing, I wear an XL (5'10 185lbs) in Castelli Jerseys and an XL in this was perfect.

Some g