This shirt is incredibly light, but is stacked full of the features you want to keep the sun from burning, whilst letting the air through to keep you cool. The stand-up collar keeps the sun off the back of your neck far better than a normal collar, while the sleeve tabs mean you can roll the sleeves up and keep them there when the risk of burning reduces.
I use them to keep the sun off and to prevent having to use shed loads of sun screen when I'm taking photographs - sun-screen really isn't good for cameras and lenses. They also keep the midges and mosquitos away far more comfortably than being smothered in repellent.
These are about the lightest shirts you can buy, so take up little of your precious luggage allowance if you go on safari. They also wash and dry in very little time at all, so you can wash them in the hotel sink or shower if you need to, hang them by the loops and have them ready for use next morning.
I have both long and short sleeved versions according to the destination. The best shirt I have ever found for travel in hot climates.