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How To Buy a Used Smartphone Without Getting Screwed
here is only best way that is bench mark you just need to install an app to that device which you are goin to buy this app will check all your mobile hardware performance like CPU .GPU, Ram etc. and rate all devices after that just check the rating of the original model on internet if rating is same then that mobile is original id rating is bellow to original model then mobile is high copy or fake
name if that app is "antutu" you can download on playstore or apple store for checking original mobile rating just search on google
(brand or model) antutu rating.
you can also check rating on antut website
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