portable high seat

Does anyone have any views on which are the best of the various portable / folding high seats on the market? By "Best" I really mean build quality / strength / durability / functionality and value for money. It is really for foxing prior to the shooting season or dealing with impromptu...

Im sure someone has asked this before but if so I can't find it! Can anyone recommend a truly portable lean-to high seat? Thanks to anyone who can give me some advice.