Space helmet with visor and telephone: what they have in common

1. Step 1. Space helmet with visor — is part of — Spacesuit. A transparent helmet with a light filter.
2. Step 2. Spacesuit — is made of — Vulcanized rubber. The pressure bladder is rubber.
3. Step 3. Vulcanized rubber — is material for — Tyre tread. The tread is rubber.
4. Step 4. Tyre tread — is made of — Carbon. With carbon black for strength.
5. Step 5. Carbon — is material for — Hearing aid. The first hearing aids used a carbon microphone.
6. Step 6. Hearing aid — evolved from — Telephone. The first electric hearing aids were built from telephone components.

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