This high-visibility vest is good to have not just when running or cycling, but any time you need to be clearly seen in dim light.
In addition to reflective strips, it also has bright LEDs in the back and front, so your safety doesn't depend on being directly lit by approaching headlights.
Made of thin mesh and weighing only 3 oz, it won't restrict movement, and has convenient cinch straps so you can quickly adjust the fit if you add or shed layers. The zippered pocket in the back has a water-resistant section that fits a wallet or cell phone.
The small/medium adjusts from 30" to 44" wide; the front is 14" long from the shoulder, while the back is 16 1/2" long. The large/extra-large adjusts from 34" to 52" wide; the front is 17" long from the shoulder, while the back is 20 1/2" long.
Machine washable and comes with two long-life button-cell batteries. A real improvement over typical safety vests.