So, check this out, the real effect of red light therapy specifically in the 660-670 range was a chemical release and change in nitric oxide from the cells. Google it. But what that meaaaanns is you get full vasodilation from about 10 minutes of exposure. I'm on my third jerk off today, hard as a rock, and barely sore, im 37. I purchased the cheap 20$ 660 and 850nm pad with Velcro straps as seen in the Kaplan thing for probably a ridiculous price. I also got the 16$ off brand flashlight with three red frequencies. Using this I have an effect like Viagra/Cialis but better about 10-15 minutes of exposure, then about 30 minutes after it's ready. To supercharge this I added a argenine citrulline (nos) complex so every time I do it it has something to pull from. I also wrapped my electric pump with the pad. And use the phallosan with the pad across the area as well. With the pad I use a power brick I owned and put it in my pocket while I'm pumping or stretching.
Tldr: red light In the 660 -680nm range causes vasodilation and release of nos(sort of how Viagra works)
You don't have to spend a lot of money.
Add nitrogen precursors or boner pills for ridiculous results.
Probably won't cause enlargement short term but will help bring out your best.