The C684H is a four-piece casting rod; the S704H and S824XH are four-piece spinning rods. The S775MH breaks down into five sections and measures just 52 cm when disassembled, while the S824XH measures 67 cm when folded.
A semi-rigid bag protects the sections. When choosing, consider both the space the rod takes up in your luggage and the length needed for casting: the longest rod isn’t always the most practical when fishing through vegetation. Check the joints after a few casts.