Reclined bicycle seat and headphones: what they have in common

1. Step 1. Reclined bicycle seat — is part of — Recumbent bicycle. A reclining seat.
2. Step 2. Recumbent bicycle — has part — Roller chain. The drive is by chain.
3. Step 3. Roller chain — is part of — Electric bicycle. The chain drive from the pedals remains.
4. Step 4. Electric bicycle — has part — Lithium-ion battery. A battery.
5. Step 5. Lithium-ion battery — is part of — Wireless earbuds. A battery.
6. Step 6. Wireless earbuds — evolved from — Headphones. Wireless headphones.

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