California Costumes Men's Hellion Horns W/Teeth,Red,One Size;  if u are bald like I am, mounting the horns on your head is a lost cause.  You will want copious hair to cover the band that holds it in place, and the replacement band after you have used it once.  The only way to glue them into place, as they are not exactly light, is with heavy skin friendly costume latex.
In my case of being bald on top and fuzzy as a teddy bear every were else the latex was not an option.  I was able to secure the to a cowboy hat with satisfactory results.  Warning:  Adding horns to a cowboy hat increases the chance of women trying to take it.  Yes I lost the hat and horns to a Betty who insisted she could stay on for more then 8 sec.