They both work as binmen in Buckinghamshire and they share a very special brotherly bond. But, that bond has become even stronger for David and Gary Cato - after Gary agreed to donate his kidney to help his big brother.
David has suffered with serious kidney problems since he was two - and its slowly got worse. Heather Edwards reports.
Portsmouth's Spinnaker Tower is be turned purple tonight to mark World Kidney Day. The NHS Trust said the area is the most generous in the country with eleven people donating their kidneys to strangers last year - eighteen percent of the total of altruistic kidney donations in 2012.
There are 7000 people on the transplant list and 300 people die a year waiting for a kidney transplant.
Since July 2007 when the first altruistic donation took place, a total of 158 altruistic kidney donations have taken place in the UK, with 21 of these taking place in Portsmouth.
Dad Mike Powis is giving his adopted son Louis a kidney. We've been given the rare chance to film the operation. This is the first of three special reports, starting tonight at 6pm, and running the rest of the week.
More than three million of us in the UK are at risk from kidney disease. Those who develop it face a restricted life of dialysis treatment and possibly an early death.