I've used a variety of Silva compasses and sadly they too often end up with air bubbles inside them in consequence of poor sealing. Suunto has a reputation for very sturdy manufacturing and so I decided to give their product a try. The reason this is a "global" compass is that in some parts of the world, notably the southern hemisphere, the Earth's magnetic pole will tend to "drag" the needle down as you stand with the compass level with your waist. This can lead to a false reading. So the global compass is designed such that it gives a clear reading anywhere. If you plan to travel outside Europe and North America it's worth paying a little extra for this design feature.