Most of them are made by scum who try to scam you for your money, preying on your insecurities.
At best, you'll have some glorified and overpriced herbal supplement, at worst you have some shit spiked with God knows what.
Stick to viagra/cialis/other vasodilators if you have ED or stamina issues.
I think it's not widely known, but since vasodilators reduce your refractory period, this means you'll have less time in between your pops, which then means you'll have more pops if you don't last long, and each one will make you last longer (well, usually that's how it works). So indirectly, it will increase your stamina.
I'm fairly young by monger standards, but if I want to party hard, meaning like 5+ girls a day, maybe even a whole day dedicated to whoring, Tijuana maybe, etc, I'll pop anywhere from 40 to 100 mg of v and it will be good for 24 hours easy. Maybe even more sometimes. It helps with tired dick after fucking for hours. Not a fan of cialis since effects are worsr but it lingers longer, I usually don't fuck like crazy for three days lol