In my experience, NDAs have been sufficient in protecting ideas during development. patents, even provisional ones must include every detail of the device. if the device is still in development, you don’t necessarily want to patent a feature that will likely change in the next prototype. therefore, if you do not have access to the necessary prototyping equipment at your company, NDAs/CDAs are ideal for development especially when dealing with prototyping/manufacturing contractors. when dealing with potential investors patents are ideal, however as many have mentioned above the NDA/CDA will serve as protection, just as I mentioned above, while communication with manufactures/prototyping contractors.