Specialized's Prime-Series Alpha Jacket is a lightweight thermal piece that offers some versatility, comfort, and clean style in a close, semi-form fit. As a standalone piece on cooler, dry days, it does function as a "jacket", but when it is colder, wetter and the conditions call for layering and flexibility it becomes more of a thermal jersey or even a base-layer. This a garment that often becomes a favorite as it eases your budget and spares you closet space, and in fact it is likely the serious user/advocate has more than one. Ideal for cyclists and riders of all kinds, even commuters, the Prime-Series Alpha Jacket taps into the fiber and textile expertise of Polartec®, bears the fabric's name, and carries design features Specialized considers standards, not upgrades.

As the Alpha Jacket features Polartec® Alpha® to bring warmth to your cold-weather days, and it is the just about the only fabric used, it deserves a detailed description. Many of Polartec's fabrics are singular offerings, with super specific qualities developed within an atmosphere of supreme fiber and textile knowledge. At the base level, Alpha has lofted fibers connected to a solid mesh core. Applied as a complete textile, it is engineered for consistent warmth, while allowing greater breathability during activity. Inherently hydrophobic, it resists all moisture and dries incredibly fast. The air exchange technology creates sustained comfort without shedding layers; it's lofted fibers keeping you warm, while allowing sweat and heat to expel from your body. It does this continuously not allowing excess body heat to build to a level that causes saturation and discomfort.

Think if it as a self regulating micro-climate that allows some cool air to pass in, circulate and carry away the moisture, while the fibers retain sustainable acceptable levels of heat. The exterior is not a blocking fabric, which is why while the Alpha is great for cool, dry days as the exterior layer, it isn't designed for rain. A simple rain shell on-board can handle that. Alpha® technology eliminates the need for a backing fabric, which allows the soft fabric to be in direct contact with your skin, so it can be used as a real base-layer as well if desired. The Alpha Jacket is super lightweight, has very low volume (bulk), and the fit keeps the overall silhouette very slim, even though it isn't a super tight racing garment. The ideal use is as a mid-layer insulating piece, but you will be grateful for the range of use.

As a mid-layer, the full-length zip, which features a garage at the top to protect your skin and/or facial hair, allows you manual control in case you do overheat or don't want to remove your shell. The neck is not extended, which makes it easier to combine with various layer and shell designs. The cut is cycling for sure, with a curved, slightly longer rear hem and shorter front to avoid bunching at the front in an aggressive riding position. The designers kept it simple as there is no pocket system, but there are reflective zones above the wrists and rear hip zones.