Propeller and zip: what they have in common

1. Step 1. Propeller — is part of — Icebreaker. Propellers.
2. Step 2. Icebreaker — uses — Wedge. The bow rides up onto the ice and crushes it.
3. Step 3. Wedge — is part of — Zip. The slider works like a wedge, bringing the teeth together and pushing them apart.

Open Evothings