The pros are familiar with a strong base, whether that's grinding out the long, solidary miles in less than idyllic conditions, forming a solid foundation to pour on the intensity that will come in handy during the racing months, or a base layer, as in the first garment placed against the skin to help stay cool when it's hot out or knock off the chill when its cold out. Castelli outfits the pros, so it too is familiar with both types of bases and offers an excellent layer in its Men's Pro Mesh Short Sleeve Base Layer. Two things really stand out with this particular base layer. One is it comes with sublimated print graphics that adds a nice splash of color you'll want to show off in the otherwise monochromic white and gray only offerings from most brands. The other is its ability to work in a really wide range of conditions. In cooler weather, the 3D mesh fabric adds a boundary layer between the jersey to trap body heat keeping you warmer, and in hotter conditions where your prone to sweat more, the layer helps transport moisture and lift the jersey eliminating the clammy, wet lycra jersey that no one likes on the top of a climb. Castelli reduces the bulk, while under an outer layer and bibs, by ensuring the waist hem stays flat. At 46 grams, there's almost no reason to not to grab this base layer as the first garment when getting dressed for the ride.