What do I need to purchase if I want to replace the HDD with an SSD?

Looking to replace the HDD in my iMac with an SSD. I have an SSD on hand but want to know do I need to purchase anything such as a temp sensor? I know older models needed some after market temp sensor otherwise the fan would run at 100% all the time. Is this still the same with this model or am I able to replace it without purchasing a sensor? What else would be recommended to make this process easier? I know I will need the little cutter that ifixit sells and some new adheasive. Any recommendations are also welcome.