Mineral insulated heating cables are made of three components:
Mineral insulated heaters are very bendable. A minimum bend radius of 5x the sheath outside diameter is recommended to not appreciably affect insulation resistance negatively.
The minimum bend radius (R) is typically determined by the outer diameter (d) of the cable times a multiplier.
For example:
Outer Diameter: 5mm
Bend radius: 25mm
Outer Diameter: 1mm
Bend radius: 5mm