The Safety Data Sheet is required by OSHA to protect the people who work with hazardous chemicals. It covers four main areas that must be presented across a 16-section format: the properties of the chemical; the health hazards posed; protective measures; and instructions for the safe handling, storage, and transportation of the chemical.
According to the relevant federal statute–The Hazard Communication Standard (HCS) (29 CFR 1910.1200(g))–“the chemical manufacturer, distributor, or importer” is responsible for providing this document. Depending on your contract manufacturer, they may assume responsibility for the creation of the SDS, they may leave it entirely to you, or they may offer to assist you with creating one.
If your product involves hazardous chemicals as raw materials, the suppliers will include their own SDS for each one, which your contract manufacturer must keep in a “readily accessible” place on-site.
Whatever your arrangement is, you have a vested interest in having an accurate, clear SDS for your product as a copy of it must ship with your hazardous product to your customer. The customer must then keep its own accessible copy of it on-site for any and all of its employees that will be working with that chemical.
For help crafting an SDS sheet, there are a number of companies in the U.S. that offer automated SDS production, including all necessary labeling.