The Mobile Warming/Fieldsheer Summit Vest, meanwhile, turned out to be a more evolved piece of apparel. Fit, feel, and comfort was more refined than the Primer shirt in nearly every area, with the warming elements feeling more effective and the materials more appropriate, finished and pleasing to the touch. The zipper closes positively, the tall collar feels perfectly plush on your neck, and the puffer-vest fit is snug but forgiving. Except for the somewhat bulky battery, I could see wearing this piece of gear every day during wintertime, and on a variety of outdoor activities to boot. The Summit Vest uses Mobile Warming’s same Bluetooth-enabled tech but in more robust 12 volt form, and therefore utilizes a larger 12 volt 5200mAh lithium-ion battery pack, which is definitely noticeable for its heft. The lightweight, 100 percent nylon outer shell though, is super-comfy, water resistant and covers a 500-fill 85/10 duck down core that kept me warm on rides below 50 degrees Fahrenheit even without the heat on. The Summit incorporates two large heating elements on the back and two on the chest, delivering temps from 135 degrees F on the high setting to 90 degrees F on low. High delivers up to 2.8 hours of heat, with 11 hours available on low. That hefty, all-new rechargeable 12 volt lithium-ion battery includes a USB port to charge mobile devices and a powerful built-in LED flashlight, but we’d forego those amenities for a smaller footprint. As with the Primer, the MW app lets you change temps and levels on the Summit wirelessly, or physically using the integrated touch control button, and we got a nice, even, all-over warmth with most applications. We were also stoked to discover a well-designed combo of interior and exterior pockets, both zipped and open, and the Summit even packs into its own stow bag (included). I’ve only had it for a few weeks so we’ll see about durability but with a non-binding, plush fit, good looks, and nice details, it’s become pretty much part of my daily winter wear.