Exhalation valve and hammer: what they have in common

1. Step 1. Exhalation valve — is part of — Respirator. It makes exhaling easier.
2. Step 2. Respirator — is made of — Vulcanized rubber. The mask is rubber.
3. Step 3. Vulcanized rubber — is material for — Reflex hammer. A rubber head.
4. Step 4. Reflex hammer — is a kind of — Hammer. A hammer.

Open Evothings