Generally they will actually say samsung on them where as the knockoffs will look exactly the same just with the name missing. Can I ask what makes you think your battery is bad? Even the very first S6s shouldn't be seeing battery issues yet unless theyve suffered some damage. Also, if you're experienced with opening the S6 on order to do this repair, may I very highly suggest you order yourself a new glass back for the phone along with your battery. Almost everyone breaks that glass the first time