I just recently got into a program that pays 20 dollars for donating human plasma.. 16 Gauge Needle but hey for 20 bucks its worth it. The way it works is they pump blood outta ya seperate the plasma and pump the blood back in. then the worst part is the cold saline being injected into u 2 replace the fluid lost. takes 4.5 mins for that and it feels like ice running into ure veins. The whole procedure takes an hour and a half. But for 20 extra bucks u cant beat it.