the tools of the/(your) trade
the things that you need to use in order to do a job.
For the modern sales executive, a car phone is one of the tools of the trade.
英语词组固定搭配大全包含18674条英汉双解词组，基本涵盖了全部常用英文词组、短语的翻译及用法，是英语学习的有利工具。