Rotary dial and parachute: what they have in common

1. Step 1. Rotary dial — has part — Spring. A return spring.
2. Step 2. Spring — is part of — Spring mattress. A spring unit.
3. Step 3. Spring mattress — has part — Wool. A layer of wool or felt over the springs keeps them from being felt.
4. Step 4. Wool — is material for — Textile. Wool.
5. Step 5. Textile — is material for — Parachute. A parachute canopy is sewn from light, strong fabric — first silk, later nylon.

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