stock-in-trade

stock-in-trade
ˌstock-in-ˈtrade noun [uncountable]
1. something that is typical of a particular person or thing, especially what they say or do:
    Stewart’s stock-in-trade was the face-to-face interview.
2. literary the things you need to do your job:
    Vanessa’s looks have been her stock-in-trade as an actress.