Weatherproof. Conditions get nasty, it has to hold up. Cheap plastic won't do, open key entry points will let moisture in.
Durable: Must handle dropping!
Easy to use: If it's a challenge, your patrol guards won't bother. Just human nature..
Easy to program: Detex makes the easiest to program systems, anywhere.
Support: If you have questions, you should not have to skype for the answer.