Whether hitting the trail for an evening run or ripping a few park laps on the bike before work, the right mid layer can mean the difference between being warm and comfortable and battling hot and cold flushes caused by trapped heat and sweat, making for an all around bummer of a time. As such, we’re big proponents of merino wool, which, as you should know by now, is celebrated for its naturally superior breathability, odor-resistance, and moisture management abilities.

As much of the country—NE included—seems stuck between season, we’ve recently added the Ellipse Jacket from Icebreaker to our arsenal for spring training. Over a recent long weekend we put the Ellipse to the test, pitting it against some of spring's colder temps at Brooklyn's Prospect Park—an outdoor haven in the midst of the concrete jungle (that's much better looking come summer).

With just a merino t-shirt as a base, the technical, lightweight jacket’s zoned chest insulation and moisture-wicking face fabric was genuinely effective, keeping us perfectly comfortable while running through Prospect's network of dirt, gravel, and paved trails. When the wind picked up and sun dropped, a shell easily fit over the Ellipse, as the sleek, slim design leaves effectively no spare fabric to bunch up.

The key to the Ellipse is its unique, ergonomic design. The hybrid, environmentally conscious construction features Icebreaker’s specially engineered MernioLOFT insulation—a natural, breathable, and super warm wool fiber-based alternative to synthetics. Unlike many common insulators, MerinoLoft retains its insulating capabilities even when wet, meaning you’re free to go hard without having to worry about heavy sweat affecting the garment’s performance.

While the insulated panels up the warmth factor, it’d be all for naught if it wasn’t for the quick-drying, super-soft merino and recycled polyester blend base fabric. The fabric has just enough give for ease of movement, making for a pleasant balance of technical and natural, celebrating the best properties of both materials.

Other standout features include zippered hand pockets and thumbloops, a small internal zippered stash pocket ideal for a bit cash for hitting the corner store on the way home, and off-shoulder stitching to prevent seam rub and improve mobility.

All in all, the technical, lightweight piece might just be the ideal mid layer for combatting chilly spring temps.