Error recognizing WebDriverWait

I'm running a unit test in C # with Selenium WebDriver and when trying to enter the code WebDriverWait it is not found. >

I'm using the namespaces below and still do not recognize them.

OpenQA.Selenium;
OpenQA.Selenium.Chrome;
System.Threading;
Selenium.WebDriver.WaitExtensions;
OpenQA.Selenium.Support.UI;