Hoo Whistle Case by Sang-hoon Lee
There are multitudes of iPhone cases out there with clever and creative designs, but the Hoo Whistle Case by Sang-hoon Lee is the best that I found so far.
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Hoo Whistle Case by Sang-hoon Lee is creatively integrated with whistle where you can actually use the whistle. According to Sang-hoon Lee, whistle is the most useful and the simplest tool that can be use in an emergency situation or in various circumstances where easily you can send signal and get help.