Its SSD and battery each have a replacement guide; a full drive and a worn cell are separate purchase costs.
What to check before buying
Storage
The 9305 SSD guide covers removing the bottom cover and swapping the drive. Reinstalling an operating system or transferring data is a separate task from fitting the module.
Battery
The battery has its own procedure and is not the same part as the 9300 or 9310 battery by name alone. Use the 9305 identifier when comparing components.