Red-Light-Therapy-Device - 45W LED Panel Deep 660nm and Near-Infrared 850nm LED Light Combo for Skin Beauty,Pain Relief of Muscles and Joints

Q: How long is the power cord, and is it a 2 or 3-prong grounded plug?

The 71-inch power cord is 2-plug.

Q: Has anyone purchased and used this item for stretch marks? Have you noticed improvement?

Red light is great for the skin overall. Although, have not seen any difference on stretch marks.

Q: What's the difference between near Fred and infrared in luminous quality

First is the difference of what you can perceive. Infrared you cannot see, it will look like the bulb is off. Near infrared will show as red light. Secondly is the wave length, infrared will go deeper into the skin and body. Both NIR and IR are beneficial for skin health. But the deeper wavelength will help with collagen production and even some studies have shown fat loss.