Mine is a qmadix boost pac case. I do like that it serves as a case which is less bulky than a regular external battery- easier to use while charging but as a case it is bulkier than a regular case, and heavier. But is it bulkier than an otter box? I don't think so? I'm also sure that if my booster wasn't actually acting as part of my phone that I'd quickly lose it. The only place I use more battery power than Disney is NYC with my daughter- all my maps, restaurant locators/ reviews, parking finder, favorite fabric shops, Central Park trivia, etc are on there. I want to take (and post) photos! And, at the end of the day, it better be working so I can text the garage and let them know I'm coming. One day, DD put a water balloon in the stroller pocket with the phone and killed it (booster was actually OK... I'm 90% sure it was on). I learned how much I use it in the city!