Think about what kinds of situations you are going to be using your phone in. A common feature of these phones is a rubber edge to keep them from being damaged if dropped. This is particularly important if you are going to be working over hard surfaces such as concrete or in high-up places like trusses. Phones that are made to be impact-resistant are more likely to survive a drop.
Along with not damaging the body, drops should not break the screen. The screen should be crack resistant as well. Also, make sure that the screen can be seen under harsh lights or in the sun.
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