get one for the vehicle you want to put it in,a check valve and a vacuum hose(which hooks up to a vacuum port on your manifold or carbeuator base.You might have to get a longer brake line to the master cylinder. I paid about $175 for the master cylinder,booster and check valve -on my 78 bronco.But tha was about 6 years ago at NAPA. If the fire wall is not set up for a brake booster-you will have to drill the holes for the booster(make sure that you do not drill into any wireing or cause any damage to anything---Look before you drill and check out everything. Yopu might also check the clearance under the hood. ---You never said what you are working on-appilications can varyI need to know what is required to put in a brake booster and what are some good brands?any help would be appreciated