The Vielight 633 Red is a compact personal photobiomodulation (PBM) device.
Its cold LED 633nm red beam is ideal for systemic photobiomodulation via photonic diffusion through the nasal blood capillaries.
The Vielight 633 Red and Vielight 655 Prime are comparable in efficacy.
The nasal cavity is rich with blood capillaries. There are more capillaries per cm2 than in most organs of the body. Five arteries connect to the nasal cavity, while the Little’s area is a frequent site of nasal bleeding. Given the rich supply of blood and the thin, permeable membrane within the nasal cavity, the light can easily reach the blood. Thus, this area is well-suited for systemic photbiomodulation which via blood.
This Vielight 633 Red device can be used in combination with the Vielight 810 : (Link)
What is systemic photobiomodulation? : (Link)
The science behind the difference between the 655 nm and 810 nm wavelengths can be found in this independent study : (Link)