Heat Shields are parts that protect a rocket from the intense heat during re-entry. They come in sizes from 4-wide to 12-wide and have a heat tolerance of 6000 degrees Celsius or about 10,800 degrees Fahrenheit. The 4-wide one is free.
They also help prevent unwanted spacecraft rotation during re-entry. This is because the air flows around the rocket, rather than bunching up and pushing on one side of the rocket.
- There was a bug that if you place a Heat Shield on a Fairing/Fairing Cone, it will adapt to the fairing. Also, if you select the fairing (cone), they won't clip. This was fixed in a later update.
- Actually, it could withstand 6180 degrees Celsius (11150 Fahrenheit), until it eventually breaks up.