I got one of these:

https://www.amazon.com/Silk-iPhone-Max-Grip-Case/dp/B07FW5BNNX/ref=sr_1_1_sspa?keywords=silk+iphone+cases&qid=1550933001&s=wireless&sr=1-1-spons&psc=1

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It's only $12, grippy, good looking and has excellent protection for a slim case.