[Closed] VR Headsets for mobiles, specifically iPhones

Looking to get my sons and nephew a VR Headset for their mobiles as a bit of fun for Christmas.

Aged between 7 and 13, looking for something inexpensive but allows adjustment to suit all ages, not too heavy and will accept a range of phones from iPhone6 to plus, ideally still in a slim protective case.

Amazon reviews swing wildly from excellent to rubbish for same item so confused as to what to buy.

Budget, ideally under £25 as I'm getting 3 of them, but will spend more for something that might extend its longevity and use.

Any experiences, recommendations? Would appreciate links to content etc

Thanks