translucent insulation

Hi,

I have some 4-core shielded cables. The insulation on 2 of them is
translucent - sort of like silicone rubber, while the other 2 are the
normal red and black. The insulation seem to be harder than those I
am used to. Cables with translucent insulation, anyone knows what are
they design for? And if they are suitable for use as cables for the
stepper motors -

i. from casing (DIN connectors) to motor
ii. from DIN connectors to gecko?

Thanks

lee