By Charlotte Whale
There's not many of us who give blood and even less of us who donate plasma and there may be many people who probably don't even know what plasma is.
It's the liquid part of your blood that carries blood cells around your body and just as crucial to saving lives.
It takes longer than giving blood so it's more of a commitment, but it's extremely important and the blood service are looking for more donors.
Bob Dawson is an ex-military man and a real Kiwi bloke but some believe he's worth his weight in gold.
For 35 years, Mr Dawson has been donating his plasma almost every two weeks.
It's Kiwis like 9-year-old Brendan who benefit from Mr Dawson's plasma donations.
Brendan's immune system doesn't work properly and he gets very sick, so he's injected with a blood product made from plasma every fortnight.
Donated plasma can be made into 13 different kinds of blood products which help people through surgery, those who have immune deficiencies, or need it on a regular basis.
Story joined Mr Dawson on his journey to the clinic and for his 500th plasma donation.
Watch the video for the full Story report.