How is the protection I considered it to but my worries where that sides where open.
Apart from the fact that it's not compatible with their own tempered glass protector, I bought both, applied the protector, later bought the case and tried to apply it but it picks up the corners of the protector, had to end up taking it back off.
Sorry to hear that... I'm using a normal tempered glass that covers all the phone although the case goes over it. Unfortunately my op2 came with it (used) so I cannot give you a name/link...
Ditto, it's my favorite! Had the one from one plus for about 6 months and in that time I dropped it twice. Both times were on carpeting and both times the phone actually popped right out if the case as it hit the floor. Luckily as I said it was on carpet, so no damage occurred. Seems the one they sent me just did not want to snap in correctly....don't think it was flaw in design, just the one I got did not quite fit perfectly. Was going to order another last month when they were half price (from one plus), but then I spotted the exact same case from amazon for only $5!! Took a chance and ordered, received in 3_weeks (from China if course) and this one fits like a glove!! Much more secure then the original one and $15 less = winner!!
Do you recommend using that case without the back of the phone.. ?
(Apart from my abusive behaviour lol. Just kidding, accidentally dropped from about 3 feet display facing down, tempered glass, display and phone was not harmed). I think that the choice I have made on buying the Spigen and GlastR was worth the money 
