The ROM part of the Marmot ROM Jacket is not like the CD-ROM you put in your CD player. In this case, ROM stands for Range of Motion, something you need and in fact require in a technical jacket. The ROM jacket is made of light, summer weight fabric called WindStopper, which is windproof, waterproof and breathes excellently. Side panels allow even more ventilation should you heat up as you run, climb or take in some spring skiing at Tahoe.Other notable features of the Marmot ROM include Angel-Wing Movement which allows the shoulders and sleeves to stretch without forcing the hem to ride up, a special Pack Pocket design that allows unhindered access to your pockets when you wear a backpack, and special cuff straps you can tighten if necessary to block out the chill. You've also got a drawstring hood for head protection and a drawstring hem for adjustability in more serious weather.Overall, the technical Marmot ROM Softshell is ideal for cool weather activities in the spring, summer and fall, but with its close-to-the-body cut and breathability, you could even wear it in the winter as a mid layer.