A light-blocking compression sleeve comes with each BSXinsight order. It's designed for the calf, but with daily workouts and tracking muscle oxygenation, it can be reversed and wrapped to other muscles.
The sizing chart is based off your calf measurement (largest area), in inches:
If you are borderline, between sizes, or like additional compression, it's recommended to go with the down-size option.
Sleeves will stretch a bit after the first few uses. While they're designed for long-term use, you can maximize their life by rinsing and hang drying vs. using a washing machine/dryer.
Additional sleeves can be purchased here: www.bsxinsight.com/sleeve