I’ve had my personal one for well over 20 years! I think I was given it by a friend who was clearing out their loft - it’s very old. The ones I use clinically came from a physiotherapy supply company, but would not suit ‘home’ use.
They seem harder to come by in the ‘states than anywhere else. But google for Phillips Infrared Lamp - I have put links on many posts about IR lamps on Thunder’s in the past. Because you can change your distance from them easily, the wattage is not critical, although around 150 seems ideal.
Heat makes the difference between gaining quickly or slowly for some guys, or between gaining slowly instead of not at all for others. And the ideal penis size is 7.6" BPEL x 5.6" Mid Girth.